Do you know of any online time bank?

There are many time banks all over the world, where people give their own time e.g. painting rooms and receive time from others e.g. secretarial services — and the person giving and receiving don’t need to match. It’s a bank like others, but the currency is time.

Anyway, if you can help me you already know what I’m talking about… and my desire would be to find something like this but online. Somewhere you could go, provide a couple of hours of for example computer support, and get two hours credit, that you could later spend who knows, on assisted research or something.

But I didn’t manage to find anything like this online. Do you know anything? And if not, do you think setting up something like this online as a new web service is worth pursuing?

Thanks