We built an internal app similar to this at a previous workplace. It was a small company and most people would go out to lunch together every day. Getting every

We built an internal app similar to this at a previous workplace. It was a small company and most people would go out to lunch together every day. Getting everyone to agree where to go was the hardest part. The app would email everyone in the office at 11am so they could opt-in or opt-out that day. Based on who was going, the app would recommend 3 restaurants from Yelp and put them up for a vote. Voting would be open for an hour and ultimately we would go to lunch at the restaurant with the most votes. We trained it to be "smart" about its recommendations, taking into consideration who was going to lunch and their previous voting history. Neat idea, and it probably could have been generalized to work for happy hour, date night, or other group events.