A general concern that I would have is that there have been various websites over the years that address this problem (the first one I remember was called something like CrushMail back in 1999 or so and the most recent was the pivot made by Breakup Notifier after Facebook shut them down (http://apps.ycombinator.com/item?id=2264660)). But often, they end up being mostly a way for people to spam their friends instead of people getting value out of it. (Typically, they ask you to enter email addresses of who you think has a crush on you. The site then uses that information to notify those people that someone has a crush on them. So when you find a 'match' it could just be that both people entered the others' name on there thinking that they might be the one to have a crush on them.)

http://en.wikipedia.org/wiki/.at