This script will apply user-entered text to the "Category" tag of each of the selected tracks. iTunes 5 or better.
(Note: In order to launch this PowerPC-era script on an Intel machine, it must first be opened and then saved using AppleScript Editor, which is located in your /Applications/Utilities/ folder. More information is here.)
Apply selected CD's CD Text to its disc and track tags
Delete characters from the beginning or ending of selected tracks' name, artist, album, comments, composer, or show tags
Capitalize the first letter of each word in selected track names
Set choice of various number tags of selected tracks incrementally
Remove iTunes tracks disassociated from files
Open the iTunes Media folder in the Finder