We've been on something of a contest kick here, so let's continue the trend. The World Bank is sponsoring the $15,000 Apps for Development contest. The World Bank launched its Open Data Initiative in April, 2010 and it's offering cash prizes to the developers who can make best use of the data.
The World Bank has been harshly criticized by non-governmental organizations, but this could be a good opportunity to for developers with ideas to do some good while making some money.
Details:
More information can be found on the official contest site.
The World Bank also recently sponsored the "alternate reality game"/contest EVOKE, which was lampooned here.