LunchApp is a website you can use at your workplace (or other group setting) in order to ensure the group is well acquainted. This was envisioned while working at a medium sized company which was in the process of decline and division as a way to lift spirits, see what other people were up to and generally meet your coworkers.

How it works is this. If you haven't gone out to lunch with an individual you're more likely to be put in a group with them. Parties are 3 or 4 by default when the number of pariticipants is greater than 5 and 2 or 3 otherwise. One participant per group is made the organizer to avoid the kind of apathy caused by diffusion of responsibility. Finally, lunch happens once a month. People have between the first and fifteenth to sign up and the rest of the month to go for lunch.

Participants are notified by email when groups are made.

Currently running here