From a purely financial perspective, it makes no sense for you to hold onto this upside-down property. Let the bank foreclose, take the ding to your credit, and get out. This is probably the rational thing for you to do.
Unfortunately your rational decision, when repeated by so many others in similar situations, will lead to a major downturn in the financial sector, which will in turn lead to a major downturn in the overall economy. At this point, though, the horse has already left the barn and there’s not much we can do about it. We’re all going to have to eat the consequences of this bubble, which — with a little proper regulation and oversight — might have been avoided.