I came across this one a few days ago. It’s a “social savings” app called Reach. You can invite a small (or large) circle of people, set a shared goal, and begin to auto-save towards it while tracking each other’s progress. Asides from the shared goal VP, I imagine it’s a great way to use peer pressure to force people to save. If I know that my “friends” can see my progress, I’m a lot less likely to be frivolous. The app’s still in beta, but do check it out when you have the time (I really mean right now).