A colleague tipped me off to an iLounge story about a piece about a free iTunes plug-in called iConcertCal that "monitors your music library and generates a personalized calendar of upcoming concerts in your city."
I downloaded and installed it and it's one of the coolest pieces of software that I've seen in a while. It works by scanning the artists in your iTunes library and then presents you with a list of upcoming concert dates (in a calendar view) for all of the artists in your library that are touring within 60 miles of you. It works as an iTunes visualizer and is one of the most creative uses of a visualizer that I've seen.
All they need to do is find a way to output the concert data to an auto-updating and it's a home run. iConcertCal is available for both Windows and Mac OS X. (Thanks David)