Store, sync and share your files from multiple computers - Dropbox

UPDATED: Dropbox is an online service which gives you 2GB free online storage to store, sync and share (if you decide to share) any type of file.  Their no nonsence approach means you get a very clean and usable interface both with their desktop application and via the website.

Syncing happens in the background, and basically anything you put in your Dropbox folder on each pc will appear on all your other PC's automatically.  It is a very intelligent system, as if the file you are deciding to store in Dropbox already exists in another user's Dropbox account, then it does not need to upload anything, as it just makes that file automatically appear in your Dropbox in a flash.  Don't worry this is done via file hashing so it ensures that even if your file names are the same, it makes sure that the actual content of the file is the same too.

If 2GB is not enough, you can upgrade to 50GB for $99 a year, the software is currently supported under Windwos, Mac and Linux, visit https://www.getdropbox.com and download it to get started.