iConcertCal is a free plug-in for iTunes that scans your music library and then gives you an up-to-date calendar of live shows in your area based on those artists. iConcertCal can help you track upcoming shows and CD releases, as well as buy show tickets and CDs. You can also export your custom concert calendar to iCal (now even in Snow Leopard), and share it with friends.
iConcertCal is designed as a "visualizer" for iTunes--a tool that usually displays colorful light shows along with your music--but you view iConcertCal in the same way. iConcertCal doesn't always guess your location correctly (it uses your IP address), but you can change that in your settings--and you also have the option of specifying a more limited subset of artists that you want iConcertCal to follow, by creating a special playlist. The primary intent of the developers behind iConcertCal is to promote live music--so you get a lot of value here for a free app, making this a must for any live music fan. iConcertCal can also now sync up with iConcertCal for iPhone, so that recommendations are based on your entire library, not just the music on your iPhone.