Four figures if you know how to negotiate and have potential buyers.
At first sight it seems like a great domain: simple, .com and leverages the growing importance of social media - enough to attract basic investment. However, when you dig deeper you find out that as you said "it used to be a great site", it's like a stock going down by the minute.
Plus, the premise of value it offers is "add friends" which can be done automatically and is heavily encouraged by existing social media platforms, making it a somewhat obsolete website unless someone wants to take it and present it in a different angle - if that is done correctly, it's a gold mine!