Interesting concept and perhaps it will become viable with some more thinking.  At this stage though I think there is still a chink in the armor.  As everyone has already agreed there is a necessity to limit to one address per person.  This is difficult enough, but there is still an issue even with this guard in place - just because you can't spend to yourself doesn't mean you can't spend back-and-forth with your friends.

Your concept kinda sounds like demurrage flipped on it's head but I wonder if this really yields any additional benefits.  Even if you could solve the aforementioned problems, would this idea introduce value above and beyond something like Freicoin?  Demurrage may feel icky because money is slowly 'lost', but for most people the indirect economic effects will easily surpass this cost and it doesn't require difficult to enforce constraints on it's users.