If you don't mind about the quality, try gaming pages. Gamers are always looking for friends who play the same games as them. Just post an 'add me' and that will save you having to send out friends requests.
If you happen to be in a gaming niche clearly this is a lot more useful.
One useful tip:
If you take the time to check who is at the top of the leader boards, that's where you will find the 'coiners'... and coiners are much better prospects than non-coiners.