How can I track detailed analytics for my iTunes Library?
Last.fm and its API opened to developers gave birth to some nice web applications. Of course, you must have an account (free) and scrobble your songs to benefit from them.  

Two of them related to analytics (I'm not a specialist, I guess there must be other ones) :
http://www.mymusichabits.com/visualize/cosmokraymer
http://lastgraph.aeracode.org/user/cosmokraymer/

The latter enables you to generate visually impressive timelines of your listening habits ...



... and play history for each of your artists