Wren - Offset your carbon footprint by saving rainforests
Carbon Interface - Measure carbon emissions with an API
YAYZY - Track the carbon footprint of each purchase in real-time
CarbonSutra - API for Estimating Carbon Emissions of Organizations
Capture - A great free screen capture utility that allows you to capture either a window or the desktop and save it to either a file or the clipboard.
Aerial - A beautiful aerial screensaver for your Mac