As far as increasing the potential number of available files, I like what BearShare has done in their latest release which is to have an auto-force ip option where if you're behind a router, it will go out to these free services to discoever your real IP address and then use that. I always force my IP, but I'd be willing to bet that a lot of people don't realize that they're assigned a different IP by a DHCP, or how to change it even if they do know.

-Chuck