Only one. Looking For Group LFG
Beautiful black humor, interesting storyline and just fun to read !
My absolute fav would be Ozy and Millie: it’s huge, has Foxes, dragons, zen, ADD, in short, it has it all! 
Also, it is complete, so it stopped updating.
But it has ended, so there’s the stuff i’m reading at the moment:
XKCD (gotta love his science-y humor)
Dan and Mab’s Furry Adventures (or DMFA)
Freefall
Dresden Codak (too awesome for words)
VG cats (whenever he updates)
Lackadaisy (its art is absolutely stunning)
Sinfest
Housepets
Order of the Stick
Gunnerkrigg Court (this guy is more than awesome)
Penny arcade
Jack (as others said, beware of gore and tremendous insight)
The abominable Charles Cristopher (this one cracks me up/makes my eyes watery every time i see it, it’s ridicously powerful)
Kukuburi
Among a lot others. Why, yes, i’m quite an addict.
I got a couple more to add.
No need for Bushido
Looking for group
inhuman (Not for everyone.)
Oddfish
Atray 3
Nicky 510
YU + ME (About dream worlds, very interesting.)
Only web-comic I read is the aforementioned XKCD. As a Comp. Sci. student, it seems like me and my coursemates are part of the intended audience.
Ah, forgot to mention that one myself! I got misty eyed myself at times. It really is powerful.
I also read Penny Arcade and Looking for Group. How could I forget those?
I knew I was forgetting to mention some.
xkcd rocks!!
cyanide and happyness is sometimes nice as well
and megatokyo of course -_^
Forgot to mention Bear Nuts. It’s like the twisted version of Carebears. It’s awesome. There’s like a Crack Bear, Evil Bear, Death Bear, Gay Bear, Prozak Bear, etc. 
Huahaa, What an awesome comic. Thanks for mentioning it! 
Schlock Mercenary
Darths and Droids
Freefall
Girl Genius
Irregular Webcomic
[Edit:]The Book of Biff -I love this one
I really like Dinosaur Comics.
This strip deserves its own post.
In the previous pages, he lived in a dream where he had a snout.
webcomics? sheeeesh.
Well: It’s worth noting that webcomics suck. Come on, lets face it. They’re all terrible. But that’s why we love them.
Anyway:
El Goonish Shive is an old forum favorite, at least with a few people (glares at shatterspike) It’s… funny. It’s pretty silly and recently decided not to take itself seriously anymore, which is a GOOD CHOICE because when it takes itself seriously, it’s pretty bad. Anyway, it’s a little on the weird side, so if you can handle weird, give it a shot.
Darths and Droids is a comic for people who like Star Wars and DnD. It’s sort of an affectionate rip-off of DM of the Rings, which is an outstandingly funny comic that i recommend to anyone who wants to learn Dungeons and Dragons, and especially to people who know a little about it and want to try being the Dungeon Master. Darths and Droids is more long-running and thus is more watered down, but it’s still good.
Saturday Morning Breakfast Cereal is a crude gag comic, basically a less funny Perry Bible Fellowship. It manages to have some great jokes once in a while, though, and is generally pretty funny. Word of warning though, the creator of the comic is outspokenly an atheist, and does not mind using his comic to make a fairly unfunny, ham-fisted jab at any sort of religious belief. Sometimes the results are hilarious, but others they are just annoying. I don’t particularly mind, and if you don’t think you will either, then go for it.
Nerf Now is a gaming comic that also does it’s best to provide fanservice up the wazoo and parody the “moe” culture of anime at the same time. It has produced some outstandingly funny strips, particularly about Mass Effect recently, and seeing the entire Zerg army as cute little anime girls is pretty heart-melting. Recommended for people who play Team Fortress 2.
High Moon is generally outstanding. It is actually published in graphic novel form (the first book recently came out, at least) but is put online as a service to it’s fans. It’s a fantasy action comic that mixes wild west with werewolf and general undead monstrosities, and does so with style and grace. It can get pretty bloody, and the plot isn’t exactly extra strength, but it’s possibly the best looking comic on the net and simply oozes cool from every direction.
I have tons more, but i’m done for now.
The only ones that I actually read every week are:
Questionable Content
Megatokyo
yu+me=dream
all fantastic.
and @Win Laik Pya, I completely dissagree with you.
there are some extremely well written webcomics,
and alot with amazing art too so…
yeah.
Aside from other ones people have already mentioned, here’s my list:
Templar, Arizona
Rice Boy and Order of Tales
Hanna Is Not a Boy’s Name
Hark! A Vagrant
FreakAngels
Cyanide and Happiness
Penny Arcade
The only ones I read on a daily (well semi-daily) basis are:
El Goonish Shive (Win Laik Pya and SlinkingFerret are to blame for that)
xkcd
Dr McNinja
Yosh!
And then of course Penny Arcade, Ctrl Alt Del, Cyanide and Happiness, VGCats, and a few others from time to time.
you know that deep down inside: if Elliot were standing on train tracks, and a train was coming, you wouldn’t even warn him, because it would take too much effort on your part.
^^ fact.
protip: no one cares about Elliot. He’s so useless.
Okay, this thread is like my kryptonite…
I once made a list of the webcomics I read, and it was maybe 2 pages long in MS word… It’ll be longer now.
Give me a minute, and I will have my list up.
EDIT: I may have missed a few, but…
+EV - Poker related jokes, pretty funny
Cool Cat Studios - a comic about a comic studio, funny, sometimes NSFW, and also finished
Cyanide and Happiness - no words can describe the awesome
Dead Winter - zombie apocalypse, with some funny comics too, very good art
El Goonish Shive - old forum favourite, transformations and silliness
God Mode - gaming comic, updates very infrequently lately
Horribleville - currently finished, absolute randomness and funny
Krakow - pretty good, a lot to read through, and pretty funny… Currently on hiatus
Least I Could Do - daily updates, great quality, very funny.
Looking For Group - by the same people who do LICD, fantasy based, very funny too
Menage a 3 - Forget love triangles, the love shape here is too complicated to describe… But also very funny
No Need For Bushido - artwork has definately improved over time… set in feudal Japan
No Pink Ponies - more random relationship stuff, as well as a comic store
No Room For Magic - fantasy realm, girl called Magic is the only one who is normal
Staccato - gaming related, but also randomness
Sorcery 101 - magic, vampires, werewolves, and great art, definately recommended
Sore Thumbs - gaming, randomness and politics all in one comic!
Strange Someone - same people from Sorcery 101, highly recommended.
The Noob - set within an MMORPG, funny comic
VG Cats - gaming hilarity from anthropomorphic cats
XKCD - maths, science, and other intellectual jokes with stick figure art.
Zap In Space - sci-fi comic with a very good storyline and great art
Two Lumps - the life of two cats, Eben and Snooch. Very funny comic
Sister Claire - A nun is made pregnant with the next coming of Jesus… And a lot of other awesome stuff
As We Were - Same people as Sorcery 101, also very recommended.
The Gun Show - same guy from Horribleville, very random and funny
Geist Panik - Supernatural comedy
Accursed Dragon - The adventures of a dragon and a woman, also funny
Super Effective - by the guy from VG Cats, pokemon related humour.
Gone With The Blastwave - very funny, but unfortunately no longer exists 
Penny Arcade - do I even need to say what this is? Gaming hilarity at its finest
Ctrl + Alt + Del - gaming and comedy again, almost as good as Penny Arcade
Crow Scare - horror tale about a giant murderous crow
Templar, Arizona - hard to describe, exactly… Interesting drama, though.
Striptease - set in a comic studio. Good humour and a convoluted story, really good.
Eerie Cuties - supernatural comedy set in a school, same person who does Menage a 3
Gunnerkrigg Court - very interesting tale set in a giant school… Contains supernatural elements
Sugar Bits - Wonderfully drawn comic by Bleedman. Looks cutesy but really isn’t.
Everafter - fairy tale characters in an asylum. Currently on hiatus
Tin - a tale of the worst ninja ever
Sinfest - Funny stuff, expect blasphemy.
Last Blood - vampires vs zombies. Need i say more?
Dreamless - a very unique and different love story, with amazing artwork
Antihero For Hire - a superhero with a big gun takes on various villains. pretty funny
Brain Dead - zombie survival comedy, very funny
Powerpuff Girls Doujin by Bleedman - same guy as Sugar Bits, very interesting story
Inverloch - fantasy drama by the artist for Dreamless, great art, great story
Marry Me - romantic comedy that is actually good!
Blue And Blond - surfing comedy, very funny
PURE - set in a world where those without special abilities are considered outcasts
School Bites - a school for vampires, also pretty funny. Great art too
The Meek - very, very interesting comic. Wonderful art and a very good storyline so far.
From Scratch - same people as Sorcery 101, looks very promising so far
Scary Go Round - lot of archives, very funny, good art style, convoluted story
Ravens Dojo - hilarious stuff, though sometimes NSFW
MS Paint Adventures - Very convoluted storylines, interesting comic with intentionally “bad” art
Weregeek - a tale of total geekiness. A must read for any other nerds out there
Hanna Is Not A Boy’s Name - Supernatural comedy, very unique art style and the story is brilliant. Funny too.
Punch An’ Pie - a relationship gone wrong, and the aftermath, also funny
Boxer Hockey - hilarious strip about an interesting new sport
String Theory - EVIL GENIUS! Awesome comic
Estrangel - guardian angels get bored too… Very funny
The Phoenix Requiem - by the same person as Dreamless and Inverloch, great art and amazing story
The Dreamland Chronicles - 3D comic set in a dreamland and reality, very good storyline
Questionable Content - funny comic with many different twists and turns in relationships… updates weekdays
Goblins: Life in their eyes - fantasy comic that doesn’t even pretend to be real, very good stuff
Rip And Teri - a spy and a schoolteacher, story is finished
Clan Of The Cats - supernatural drama/horror, very good art and storyline
Chopping Block - a single-panel style comic about a serial killer, very funny
Zombie Hunters - awesome comic with great art, and a very interesting storyline
Freakangels - this comic is amazing. Go read it. NOW.
Walking The Lethe - supernatural comic, with a very unique style
Emergency Exit - It’s hard to describe. Funny, though.
Locus - demons… Lots and lots of demons… Also frequently NSFW.
Bear Nuts - Great comedy comic about bears in a zoo… Tanked is my favourite bear
Paradox - a gay romance, fantasy, also NSFW in places.
Asylum Ink - very morbid but interesting comic, quite gory
Romantically Apocalyptic - set after a nuclear apocalypse, very funny with phenomenal art
Spinerette - same guy as Krakow, but with better art. Woman gets superpowers, and the comic is very funny
Also, I am working on making my own, with Tundra.
I’m liking Spinerette now that Krakov bit the dust!
you, and everyone else, should definitely check out High Moon.