jalada on Bitfriends allows you to buy/sell bitcoin between facebook friends (Not affiliated, just thought it was cool) - http://www.reddit.com/r...
"BitFriends is more about discovering friends of friends that are interested in Bitcoin (or crypto-currency in general) that you might not realise are interested / know. Because you have a mutual friend, there is a potential for a trusted, out of band (no middleman!), transaction that some may consider safer than using flaky exchanges. Not only that but it’s generally more constructive to the ecosystem because it’s more about helping people out and less about turning a quick profit. But thanks for your feedback :)" - Jalada