Renaming and Organizing Files in iTunes
I use [Rename Files][3] to keep files renamed and [Organize Files][4] to keep everything the way I want it to be. Mac only, they are available right from iTunes and do the job quick.
They allow you to rename and organize files based on any of the ID3 tag data items, including some basic if-then logic and limited reformatting. (Yes, I might be a bit biased since I am the author of both of these tools.)
_Response to the [LifeHacker][0] post on [Keep iTunes 8 from Starting Filenames with Track Numbers][1]._
[0]: http://lifehacker.com/
[1]: http://lifehacker.com/5058475/keep-itunes-8-from-starting-filenames-with-track-numbers#c8124370
[3]: http://applescript.plaidcow.net/iTunes/RenameFiles/
[4]: http://applescript.plaidcow.net/iTunes/OrganizeFiles/