xkcd
Penny-Arcade
PvP Online
Questionable Content
Dinosaur Comics
Men In Hats
VG Cats
Dominic Deegan
PartiallyClips
Perry Bible Fellowship
Order of the Stick
Polymer City Chronicles
CAD
Press Start To Play
Ghastly's Ghastly Comic (Discontinued)
Sexy Losers (Discontinued)
Our Home Planet
Cyanide and Happiness

And possibly my fave;
Gone with the Blastwave