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.)
App displays files in iTunes Media folder which are not in iTunes library
Edit tags of stream URL tracks
Remove iTunes tracks disassociated from files
Juxtapose text in Artist tag such that "Ellington, Duke" becomes "Duke Ellington"
Set the Plays of selected tracks.
Update subscriptions which have expired by virtue of being ignored for five or more days