Lastmusicmap.com is a beta webapp, please keep this in mind! It could have problems with old browsers.
The Last(.fm) Music Map is a mashup between Last.fm (Audioscrobbler) and Google Maps APIs. (Twitter SPY is another mashup I created)
Start by typing your preferred artist or a location in the input field above and hit enter (or let autocomplete do its work). Every artist's events will be displayed on the map and you can add as many artist or locations as you want. I hope you like it :) Feedback are very welcome. Thank you and thanks a lot to Last.fm!
Try Twitter Music!