These are just a few of the great apps out there--I'd love it if you would share your favorites with me too.
PaparKarma Take a picture of your junk mail, they'll remove you from the mailing list.
eCycling Center//Mail In, Drop-Off, Pick Up Options
Electronics Recycling //Find Local Options
Electronics Take Back Coalition // Promotes green design and responsible electronics recycling.
Gardening Toolkit (iTunes)
Fast Company United States of Design (iTunes)
Solar Checker Determines Solar Levels (iTunes)
Vegan Yum Yum (iTunes)