I can't believe it hasn't been mentioned yet:
Freefall
Sam the Alien, Hex the Robot, Florance the Wolf
One wants to fix the ship. One wants to pet the doggy. And one simply want to make things more interesting for everyone else on the planet.
Currently at strip 1655. Updates every Monday, Wednesday and Friday.
Yet Another Fantasy Gamer Comic
A send up of tabletop fantasy games.
Just like all the others. Except funny. And with more titties.
Currently at strip 909. Updates daily.
DMFA
Jack might be the comic behind Fel's avatar, but this is the artist who actually drew it!
A furry comic, like Jack and Sabrina. Started out as adventure, then become sitcom, now it's... Epic. Fans of Jack and DMFA have had a hateathon going for a while now as to which is the best furry comic ever. Most others have long since declared it joint first place. See also
Able's Backstory] for a less happy view of this world.
Currently on strip 858. Updates either three or 5 times a week, depending on how much of the artist's homework the mows eat.
[url=http://cyantian.net/]Cyantian Cronicles
A set of interlinked comics, each with hundreds of pages.
Bit of a mixed bag. All the comics are great - and pretty much all of them are unfinished. Reading what's there will still provide days of entertainment though.
More strips than I can easily count. Updates irregularly.
Sequential Art
Human, cat, penguin, squirrel - and an army of demonic shadow puppets hell bent on world domination.
The author's avatar is a small hamster. The reason for this is what makes the comic so good.
Currently at 489.
Daily Coyote
Ongoing blog of a woman, a tomcat and a coyote. Recently joined by a collie.
No, seriously. This is a blog, not a comic. No drawing or SFX involved.
Wonderfully interesting to anyone who is interested about animal behavior.
Updates daily. Of course. Been ongoing for a year or two. I'll be getting the book for christmas.
The Dreamland Chronicles
Proof that you don't need to draw well to create your own comic. You just need lots of skill with CGI instead.
Again more strips than I can count. Daily updates.
Kaspall
Think of a kinda-evil version of Narnia, where enough creatures from different worlds have fallen through enough wardrobes to make it possible for them to set up a civilisation, complete with people whose job it is to help people who have recently fallen through wardrobes come to terms with the fact that they can never go home again. Also a land of long and twisty arc plots. A group of police officers have to find out what is killing people. Two students have to learn why some of the dreams seem to be thinking for themselves.
Updates weekly and is currently at #207
Alpha Shade
Another pair of long and twisty plot arcs. There's our world, and this other one. The other world has flying battleships, biplane fighters and talking house cats. Then there's our world, where they have talking panthers instead of housecats, witches and other things. And this bunch of teenagers who seem quite unaware of what's happening.
Been going for years. Sporadic updates.
The Wotch
Anne is a Wotch. Like Buffy a Slayer. The last in a long list of stupidly powerful witches. There might be a reincarnation thing going on. The big bad seems to think so, as one of the reasons he keeps sending monsters after her is to 'train her up' for some dark and malevolent task. The rest of the cast is... variable. They change shape. And species. And gender. Regularly. And do other normal boring teenage stuff like fight monsters, get crushes, and hang out.
Been going for years. Biweekly updates.
Crossworlds
Fantasy adventure comic in a world where humans are impossible. No elves or dwarfs either. Where all the
interesting fantasy races live and hang out. By the same artist who brought you
Naga's Den. (Not a comic.) Two major and a few minor plots finished.
Red vs Blue
Godlike. Basically the plot of Be Kind, Rewind - but in real life. The entire Reconstruction Arc is available on their site, and is worth watching, though it might spoil some of the earlier videos. Their short video about the incredible edible internet should give you a good introduction to
their sense of humour
Zero Punctuation
Beyond godlike. A meme and creator of memes. Yahtzee is a vain, opinionated, harsh, and unforgiving critic, and can hold his breath a very long time.