http://www.dropbox.com/

Features:

Any file you save to Dropbox also instantly saves to your computers, phones, and the Dropbox website.

* 2GB of Dropbox for free, with subscriptions up to 100GB available.
* Your files are always available from the secure Dropbox website.
* Dropbox works with Windows, Mac, Linux, iPad, iPhone, Android and BlackBerry.
* Works even when offline. You always have your files, whether or not you have a connection.
* Dropbox transfers just the parts of a file that change (not the whole thing).
* Manually set bandwidth limits -- Dropbox won't hog your connection.