Just want to give props to iConcertCal:

iConcertCal is a free iTunes plug-in that monitors your music library and generates a personalized calendar of upcoming concerts in your city. It is available for both Windows and Mac OS X and supports worldwide searches.

It simply runs inside iTunes and notifies you of all the concerts of your favorite artists when they are performing in your town.

I listen to some obsecure music and lots of non-US stuff, and so far so good.  Not exactly clear if it’s handling languages other than english though.