If I wasn't whoring out my Brawl tournament, my sig would still be an image from a Married to the Sea.

The only ones I read with a lot of regularity are:
Penny-Arcade
Married to the Sea
Toothpaste for Dinner
Natalie Dee
Super Mega

I also from time to time read back catalogues of Perry Bible Fellowship and xkcd, but for some reason don't have them bookmarked. Love 'em, though.

I really need to read Order of the Stick. For some reason I just haven't started on it beyond one night when one of the guys at school literally sat me down at his computer and made me read them until we started our weekly D&D session.