I'll put in a plug for Archipelago [http://archipelagocomic.com/comic/?id=1]. It's a fantasy comic that features submarine pirates, magitech, demons, were-sharks, and an impressive amount of thought put into the cultures of the different islands. It's story is simplistic and lighthearted, but it's still emotional and epic. Hands down my favorite. The art starts out a bit shoddy, but gets much better over the comic's run.
And if you like game comics, you'd be remiss not to check out Brawl in the Family. [http://brawlinthefamily.keenspot.com/] Good, lighthearted humor and extreme knowledge of all things nintendo and how to make fun of them, with Kirby being the prime target/protagonist.
As far as gamer comics go, this one is only surpassed by Nerf Now! in my book. I love this one.
StupidFox, [http://stupidfox.net/] Slightly Damned, [http://www.sdamned.com/] Weregeek, [http://www.weregeek.com/] Skin Deep, [http://www.skindeepcomic.com/] Fairy Tale Rejects, [http://the-greys.deviantart.com/gallery/29370681] just to name my top few that haven't been mentioned already.