Well this is new to me, a little service called "numbr" that provides you with a temporary call-in number that you can forward to up to two other numbers (of your own). It's meant for online listings primarily - i.e. if you're selling something on craigslist and you're not keen on publishing your actual phone numbers. The service is free while in beta and offers a few features like blocking non-caller ID numbers, do not disturb times, and it will even forward you a log of your call history via email. Pretty slick.
You can't call out with the number, however, which is probably for the best.