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.)
Applet compels you to rate unrated current track
Copy chosen tag info from one set of tracks to a different set of tracks
Applet assists with swapping, copying, appending data between track tags
Perform search-and-replace on text in your choice of tags
Append user-entered text to beginning or ending of selected tag of each selected track
Make one big playlist from many using original track order