Been meaning to post this for a while: Wesabe. There’s a good tour describing the app.
Wesabe is a community of people who share our experiences with our money so we can help each other make better financial decisions. We do this by aggregating and analyzing our community members’ personal financial data, and showing tips — recommendations to get the most from our money. These tips and recommendations come from the collective wisdom of our entire community. When one of us figures out how to make a great decision, we all learn.
Really interesting approach, requiring great trust, with potentially strong benefits to the participants.