We've always liked the idea of using nice bugs to kill icky bugs; we've tried repeatedly to hatch praying mantises in the greenhouse, with no success.
So we got ladybugs. Ladybugs love to eat aphids, so we gave them a bit of a feast.
For one day, we had ladybugs everywhere, and from their activities as soon as they were released, we may have baby ladybugs awfully soon as well.
The second day, there were a few ladybugs still around, but almost no aphids, too.
Too early to say if it worked, but it was fun!