I'm going to set up a nice PHP script soon on my site that allows people to upload any files they want to mirror off of my site, completely ad-free. However, because that kind of service might start getting 'expensive' on my bandwidth, I'm going to leave it as an invite only system, at least for now until I can take the load easier, probably when I install a server in my home. The only thing I can imagine it not allowing to upload as it stands are script files which would run server side and allow a cracker to enter into my server unattended. As long as that's out, I think it should be okay (and an invite-only system would make it pretty easy to keep unsavoury folks out.)
Basically make a nice image/file hoster, completely free and ad-less, because none of such exist.
- Zeke