Dropbox 1.4.1 - Online synchronization tool with Finder integration; free 2 GB account.. (Free): "
Dropbox is an application that creates a special Finder folder that automatically syncs online and between your computers. It allows you to both backup files and keep them up-to-date between systems.
The Dropbox application is available for Mac OS X, Windows, and Linux. A video on the site explains more.
- Fix Dropbox not starting on OS X
- Mac OS X 10.4 or later
(Via MacUpdate - Mac OS X.)