Anyone know any good file sharing programs?

Yes, I do.

It depends on what you mean by "file sharing".

If you're talking about public peer-to-peer filesharing, the currently most popular protocol by far is BitTorrent, for which there are numerous clients available. I recommend uTorrent (Windows only) or Deluge (cross-platform).

If you're talking about private filesharing, then you should look into a file hosting service like Dropbox or Google Docs. I recommend Dropbox. It was initially designed to share your personal files across multiple computers, but you can share folders with other users, and create public folders accessible to everyone. Dropbox has a higher file size limit (unlimited using the Dropbox client) than Google Docs (1GB), and once set up acts like a folder on your computer and therefore very easy to use.

There are literally hundreds out there. You need to be more specific. File type; file size, private/ public share, long term share, and free vs paid share, how important is security?

think about those issues first then do a simple Google search with the preferences required.

For public or private use and to share what?

Dropbox - https://www.dropbox.com/ - 2Gb free

Google Docs - http://docs.google.com/ - 1Gb free

Skydrive - http://skydrive.com/ - 25Gb free

All three allow you to share files with whoever you want or you can make them public.