This exists already to some degree already - it's called a gift card, although gift cards are missing an important element of being able to be traded at multiple places.

This is interesting to read, but I don't think it will work. First, forcing people to spend seems immoral, second his "negative interest" is called inflation, and it already exists in ordinary currency.

Presumably stores will be able to redeem the scrip for regular money right? So I can just imagine a store allowing currency exchanges, pay a small fee (less than the monthly fee) and get real money.

The whole thing doesn't seem right to me. And I think the examples don't prove anything - I bet those recoveries would have worked if they used regular money, and on top of that cities can issue IOU's right now, which effectively do the same thing.

And finally the economic problems are global, not local, fixing things locally might not do enough.