Most of the feature suggestions I was going to make have already been made so I won't re-hash that. I would like to add before I get into my suggestion, that if you look at a now defunct application called "PixMaker" from a now defunct company called PixAround you can learn a lot about many of the feature suggestions posted on this forum. I purchased a copy of PixMaker years ago and still have it. You can download a free version on the net (you just can't save) at some sites out there for comparison.
Now on to my suggestion...
How about creating a community web (literally) of Photosynths that allows for synths to be linked and filled in in order to create the virtual view of an entire community. You could do this via geocode enterperlation or simply from Photosynth from one image on one section to the image in a Photosynth for another section.