> plants virtual trees (you can pay to plant real ones too) for every time interval when you stayed focused.

One of my many pet-projects-I'll-never-implement is creating one of these addicting Facebook-driven social games like Farmville (I have no idea what it's modern equivalent is) and instead of distributing profit from ad revenue / in-app purchases, donate all of it to an NGO that does IRL whatever people are doing online. So if planting an in-game tree generates $0.02 in profit from ad revenue / in-app purchases (after operating expenses, taxes, capex, etc) and planting a tree in real life costs $20, the NGO would plant one real tree after users plant 1,000 online trees

I think it's a killer idea for a socially-conscious app and I think users would feel incentivized to play this over any of the stupid casual online games with no positive real-life implications.