What if you could geo-code every song you heard on your iPhone/MP3 device and share it with everyone? Could we then build geo-location based music playlists? Know any sites that already do something like this?
Last.fm to some extent supports basic geo-information and can provide recommendations for events and show the top artists and tracks for each country. But what I am thinking of is more detailed than this: Sort of like saying "Hey! I wonder what are the cool music vibes at San Fransisco right now?" or when sitting at the waterfront in downtown Baltimore; "I wonder what folks like to listen to while watching the ocean?".
We geo-tag our images, videos and profiles -- so why not music too? Imagine going on a road trip and "tuning in to" to any "local station" as you travel from one state to another. Or a heat-map interface that would show the type of music that is trendy in each location -- and the ability to query which are the top songs for any place by genre. I think Last.fm would be a great platform to implement this, since they perhaps already have a location associated with each profile.
BTW, here is a Google Maps mashup built using the Last.fm API that shows which are the two countries that have the most similar musical taste. If you know any cool music+geolocation mashup sites, I would love to know about them!