Dropbox

Dropbox: One of the best inventions. It synchronizes your files online, and keeps versions for 30 days for free. It is extremely easy to use: After installation it creates a Dropbox folder. Just copy any files you want to that folder, and they are synchronized. You don’t need to change anything, just change the folder name you use.

Join through this link for extra 250MB free space (on top of 2GB)

https://www.getdropbox.com/referrals/NTIxODM4MjM5

Important trick: For using it under linux with no root access, download it from (or find a newer build in the forums)
http://forums.getdropbox.com/topic.php?id=12922&replies=67#post-81845
Unzip, untar and run
~/.dropbox-dist/dropbox