A good idea, indeed. Another thing that comes to mind is the time it would no doubt take to win reasonable traffic to such a site. Myspace has been recently inundated with spam so many people are not bothering to separate legitimate deals from trojan horses. You'd also possibly need some kind of "in" to your local circles on myspace, unless you already have this worked out.

I wonder if Facebook, which is now gaining popularity over myspace, could ever accommodate such a model. Like the creation of a web app that updates with said coupons every so often. Then again facebook has been clamped down pretty tightly against ads.