design for the other 90%

If Wall Street's excesses contributed to the decline of the nation's economy, could the same profit-driven environment really spawn a new generation of do-gooders?

Flood irrigation: that's how poor farmers in developing countries usually water their crops. It's wasteful and too water-intensive to work in the dry season, but until recently there haven't been other viable options — a traditional drip irrigation system could cost thousands of dollars.