I enjoyed
Exploitation Now. Though it's now done. (I never got into the author's next project, Errant Story.)
There's also
Sluggy Freelance.
I've also been a fan of
Girl Genius, which was NOT a web comic until this week. But they are now putting out their new matterial online, and simultaneously putting out the back story from vols. 1 - 13 of the original comic book version out so that people can catch up.