I'm currently developing a location based social network in Ruby on Rails. I also want to include a recommendation system. For testing the algorithms of this recommendations I need some real, anonymous training data. I've found the data from the [Netflix Prize](http://www.cs.uic.edu/~liub/KDD-cup-2007/KDD-cup-2007-who-rated-what-in-2006-answers.txt), but they are only including .

I'm searching for data that includes

* users
* friendships
* locations or venues
* check-ins (like in foursquare)

Does anybody know a good source for such data? Or a proven algorithm for generating this data? Or any other idea?