Budgt - Track your ramen spending (iOS)
Tworlds - Swap photos with strangers around the world, anonymously
Lunch Money - A personal budgeting tool with multi-currency support
Just a Minute - A web experiment to see how well you can estimate a minute.
Pennies - Incredibly simple personal budgeting app for iOS
The Evolution of Trust - an interactive guide to the game theory of why & how we trust each other