Wren - Offset your carbon footprint by saving rainforests
YAYZY - Track the carbon footprint of each purchase in real-time
Klima - Go carbon neutral
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.
Trip to Carbon - A carbon footprint calculation API for travel.
Treepoints - Fight climate change and earn rewards