Splitwise - Splitwise is a free tool for friends and roommates to track bills and other shared expenses, so that everyone gets paid back. On the web, iPhone, and Android!
Klima - Go carbon neutral
Kittysplit - The easiest way of sharing costs with a group of friends
Website Carbon Calculator - Find out the how much CO2 your website emits
ihatemoney - Manage your shared expenses, easily
Padbury Clock Screensaver - Minimal screensaver for Mac