My husband's at
www.FlashbackUniverse.com.
Although he would correct me and say this is a DIGITAL comic and not a typical web comic. The difference being, the way I understand it, is that web comics are doled out bit by bit, whereas Flashback is uploaded to the net in a fully finished form and you download it (for free) to your computer. You get an entire finished story in one shot.
Also, the comics are formatted in CBR (Comic Book Reader), so they are a pleasure to read on the screen. They are formatted and designed for that media, so no clunky PDFs to scroll through.
He's got (I think) 7 finished stories on there right now and is gearing up to put a new one out soon.
Anyways, it's a comic and it's on the web.
Also, a friend (who actually joined this site not too long ago, though he doesn't post much) does Twisted Kaiju Theater at
www.neomonsterisland.com. Here's a write up on Wikipedia about that one:
http://en.wikipedia.org/wiki/Twisted_Kaiju_Theater
Oh, and I should probably mention
www.Zuda.com. Monthly "Americal Idol" for web comics. :-D