I'm interested in the possibility of working to set this up. This seems like a very very good idea. Nothing would be more glaring to me personally than to receive a letter back from the government saying I can't know what they have on me. I think many people would feel similarly.
But I think it will only work if it really is as easy as filling out a form or a fairly easy PDF/etc.
If so, perhaps something as simple as a nice domain and a pretty WP theme with some well-written copy could turn this idea to reality...
Any other takers?