I was recently invited to try out Wuala by AJ, it poses as a file backup, sharing and social network service but upon further inspection its basically a P2P application. The great thing about it is that files are distributed on the cloud and users can 'sell' their idle hard disks space to other users.
You can find a step by step installation guide for Wuala at AJ's blog.
First thing I did after installing and sign-up is find warez; and without fail... I found ThePirateBay!
Wuala, thank you. Long live the warez!
If you need invites, please leave a comment.