Could you add the feature for users to view the categories expanded or collapsed as the dafault setting (just like the feature users to view topics flat or threaded as the default setting) in the User Control Panel?
Pretty-pink jazz > Boring-brown country music
Dixie Narco vending machines > Vendo and Royal Vendors vending machines
Boeing 767-400 > Airbus A330
Delta Airlines > All other airlines
HP printers > All other pritners
