I first learned about Time Banks in this Sept/Oct 2009 Ode magazine article. Finally blogging about it:)
From Autumn Rooney, who started the Time Bank in Los Angeles' Echo Park neighborhood:
The goal is to get people to trust each other and to think differently about value. Our current money system encourages competition, hoarding and scarcity. Time banking is different. We'll never run out of time dollars, as long as there are people.
Of course Time Banks was founded by an Ashoka Fellow - Edgar Cahn. To find a Time Bank near you check this out.