An online banking app with high-interest savings and an emphasis on green investments.
Link is a referral.
A search engine (really a wrapper for Bing) that puts its ad revenue towards planting trees.
A productivity app that rewards you for putting down your phone for a length of time you specify. If you pay for the pro version, you can fund the planting of real trees.
A service that rewards users for reducing energy usage during hours of high strain on the grid. Pairs well with smart devices and a love of gamification.
Link is a referral.