iConcertCal
If you looking for a neat iTunes plug-in then this might be the one for you. iConcertCal will scan your iTunes music and will check with several concert/tour databases on the web for concerts that bands in your iTunes library are in. It goes a step further and limits its results to within 75 miles of where you’re located too!
Of course you can change how far it looks out in miles, the state and town.
iConcertCal is a free piece of software you can download from here. While it doesn’t have support for exporting its results to iCal, the developers said it’s something they’re thinking about adding in, in the future.
It works on both the Windows and Mac versions of iTunes.