A fully-formed idea is a beauty to behold. Find the kind that works in full strength on a number of levels, simultaneously fulfilling a range of needs, and you've got an effort worthy of putting full energy into.
Such is the Playpump -- as Maura Welch explains (in the Boston Globe Business Filter, from a post in PSFK), "This genius invention delivers clean drinking water to African villages -- and it's powered by a merry-go-round."
PSFK writes, "While children are playing on a merry-go-round, up to 1,400 liters of clean water can be pumped into a tank that stands seven meters above the ground. The tank’s walls are used to place ad billboards while two sides are reserved for educational messages. The revenue from ad-sales is put into the maintenance of each pump."
Here's a device which supplies a vital necessity, and is powered by children doing what they're supposed to do, and do best: play. Talk about "Serious Fun"! As Welch writes, "Simple things are powerful."
National Geographic's "Wild Chronicles" feature on the PlayPump Water System:
Of course, now that the kids don't need to carry water from dirty streams every day, the adults are glad they can spend more time in school. From the children's point of view, this might seem like a mixed blessing. But hey, they get a merry-go-round!