"It's such a great, simple idea: Young Brazilians want to learn English. Elderly Americans living in retirement homes just want someone to talk to. Why not connect them? FCB Brazil did just that with its "Speaking Exchange" project for CNA language schools."

This is such a perfect example of what I call “symbiotic interaction," where both users benefit from each other while individual user’s goals are different from each other — mediated by a system.