I'm completely intrigued by the idea of complementary currencies. The most familiar of these are things like membership reward points, frequent flier miles, or time banks. Reimagining Money has a wonderful resource list of information about complementary or innovative currencies. Here's a database and map of complementary currency initiatives.
In addition to the logo similarity between Complementary Currency (two "c's") and the logo for Creative Commons (two "c's") there is an exciting opportunity to bring these movements together and perhaps create an economy designed to support and sustain the common good.