Using happn is as simple as signing up for the service through Facebook and leaving the app running in the background on your phone. From then on, whenever a person who also has the app installed is nearby, you'll receive a notification.
In happn's settings, you can indicate the type of people you'd like to meet. That way, you can set it up so you only receive notifications for men or women, or people in a particular age range (for example, 18–28).
After receiving the notification, you can start chatting with that person, and, in a few seconds, decide whether you want to continue talking face-to-face.
happn is a different sort of app for meeting new people, though it only works if you are really close to other users. Nevertheless, you might find it to be quite useful.
Requires Android 3.0 or higher