I think it would be much more inviting if you could at least search for people without having made an account. As it stands I have no idea what kind of people I could talk to, so I have no idea if it would be worth giving up my email address.

Edit: Interesting idea, though. With social networks like Facebook you really need to have met in order to befriend — it doesn't encourage random meetings. When I was younger I would find likeminded people by chance on odd websites; I think that's become harder as I've grown older.