I find it a pretty cool site if you are going out on a travel and is interested in doing other things than just visiting museums.
I'm very fond of trying out bungee jumps myself when I'm traveling so this site seems to help me find some that I haven't tried yet - well I might even try some whitewater rafting next time.
The site still needs some content, but they've made it possible for anyone to upload videoes and share new activities (a bit like you know from YouTube), so that won't be a future problem imo.
Cheers