Dropbox has free online storage for users, up to 2 Gigs.

Installed on multiple computers, I use it to transfer files and programs to my new computer.

I use it to have automatically updated files on multiple computers.

I can access my files that are also stored online at: DropBox.com

In addition, DropBox has industrial strength versions for an annual or monthly fee.

They say that an iPhone app is on its way, too.