I highly recommend Girl Genius Online. It's a science fiction steampunk style series, available for free online, or you can buy it in comic book or .pdf format.
It's a comic book featuring the art of Phil Foglio, best known for his MythAdventures artwork, Magic: The Gathering cards, and other comics.
This series has been around for about five years, and he continues to release three pages a week (on M, W, F).
Thanks to Brad for the link.