Social networking is huge right now - can't you picture a site dedicated to people who want their "friends" to know they like them as more than friends or something?
That said, I'd say mid-xx is about right, given that .us hasn't really arrived yet.
My advice is to keep it. Long term it can be worth much more.
I've never been a fan of .us but some nice phrases can be made from the extension.
e.g. firstb.us (firstbus is a major player in the UK transport industry)
At time of posting firstb.us is available to hand reg. I'm guessing the unscrupulous fraternity will race to reg this
EDIT.... Let's have a countdown to see how long it remains available :sold:
I have a few adult domains in the .us extension. I'll leave it to your imagination what they are, but many verbs.us are still available :hehe: