I’ve been playing around with a little social places site at weheartplaces. One thing I’m really proud of is the streetview-based navigation. When you’re viewing a place, you can spin around, and there’s a little hyperlink over other places nearby. Hover over that hyperlink and you can see the name and address of the place, and click then link to zoom through to that place page, where you can edit the details or comment on the place.
It’s a nice little bit of UI. I’ve been tempted to try and get it going against the foursquare api, then you could browse the world via streetview anywhere in the world - but to be honest, google maps already does a pretty good job of streetview.