UPDATED: De-Genre v2.0
Eliminate superfluous Genre names fast with De-Genre v2.0. This script re-assigns the Library tracks of selected Genres to another Genre so that the original--and consequently un-assigned--Genres disappear from iTunes' Genre pop-up list. As you may know, you can make many superfluous Genres vanish from iTunes' Genres pop-up list simply by eliminating a reference to them in your tracks; when no tracks are assigned to a particular Genre, that Genre will be dropped from the list. (iTunes original Genre names cannot be removed this way; only those accumulated from other sources or created by you.)