Killer iPhone App: Briefcase
Easily the best over the air file sharing/download app for iPhone and iPod Touch I’ve seen yet because there is no desktop client app and you can browse your computer’s hard drive for files on your iPhone. There is a free lite version with most of the features, and the full version is only $4.99.
It’s got a few bugs; the options screen sometimes will pop-up while you are browsing file directories. The option to save your login password is also too easily checked, and as far as I can tell there is no way make it forget your password.
So far my only feature request would be; to be able to view supported files without downloading them (streaming) the same way “iPhone remote” allows.

Make sure you get a good look at the user manual first because you must enable remote login on your Mac to connect.