This thread is a little old, but I'm surprised no one has mentioned nearlyfreespeech.net. They use a prepaid, usage-based pricing model. I've used them to host a number of minisites and other small sites before upgrading my GoDaddy hosting to unlimited domains. Never had any problem with their service as far as I can remember. It doesn't have cPanel though. You'd have to get use to their proprietary panel, and somewhat different means of operation in general. Also, if I recall correctly, they don't offer email on domains but do have some sort of forwarding. I never needed to use that, though.
Once in a while the hosting would be a bit slow for me. I definitely recommend them for high quantities of low to mid traffic sites, though. If it's a type of site where it's crucial to be at full speed at all times, you probably won't want to go with them. Also, if you're doing more than a few GB per month, you might as well use another company as you may get a better deal that way.
