I recently added a bunch of comics from the Tapestry Comics feed list. You can see all the comics I read via LJ on my comics friends page. The one above is Everybody Loves Eric Raymond, lovesraymond. It's only likely to be funny to people who are into open source software, but most of the comics have links explaining the references.
I created aproposomething which changes the captions on old superhero comics (among other blog postings). Their RSS feed was pretty long, so about half of the page linked above is that backlog.
Other comics I'd like to highlight:
sfhamlet Stick Figure Hamlet (they're currently wrapping up the play-within-a-play scene)
catandgirl Cat and Girl
dieselsweet Diesel Sweeties (web version and print version)
redmeat_rss Red Meat