"You like someone. They're in a relationship. Be the first to know when they're out of it." That's what the Facebook Breakup Notifier promises to do for you. 

Developed by Dan Loewenherz, the Breakup Notifier allows users to pick people in their friends list whose relationship status they would like to keep track of. If anything changes, the user gets notified via e-mail. 

So, for example, if you've been hoping and wishing that girl you've been crushing on would dump her lame-ass boyfriend, now you don't have to keep checking her page to see if she's "no longer in a relationship." You can just sit back and wait for it happen. 

Stalking just got a little easier.