OnlineComics.net hosts comics, I believe. I think you already have to have the pages posted, but you could run them through Geocities or the like and then advertise them through the site.
At least, I think you could do that. :unsure:
EDIT: KeenSpace has its own
free webcomic provider. Formerly known as KeenSpot, it now goes by the name of
Comic Genesis. Worth checking out, especially if you plan on upgrading to KeenSpace later on when you can afford it. As far as I've seen, KeenSpace seems to be the most comic friendly provider, and there doesn't seem to be any restriction to page layout, which is a plus.