First of all, named playlists take priority over everything else. For example if you have a playlist named Alternative Rock, then when you press the [A] key, iTunes will highlight that playlist. If you have no playlist that starts with an A, then it will take you to Audiobooks ... unless you have no Audiobooks, then it will take you to the "iTunes Store". See what I mean by seemingly random.
I have put together a list of shortcuts and the items they activate below (assuming that you have no playlists that start with that letter):
- Movies - [K], [L], [J], [M]
- TV Shows - [T]
- Audiobooks - [;], ["], []
- Radio - [R], [Q]
- iTunes Store - [F], [I], [E], [B], [H], [G], [D], [A], [C]

