About a month or so ago, I found the ultimate iTunes plugin, and I have come to realize I simply cannot live without it these days.
It allows you to set system global hotkeys for 'next track / previous track / pause/play' as well as the various levels of song raiting, and does transparent popup overlays (like how Apple's own stuff does the volume and brightness overlays). It can put a prev / play / next buttonset into your menubar. And it will go out and find the album artwork for any songs missing album artwork, and will toss a little transparent window up showing which song is currently playing when the song changes. I can hide or restore iTunes with a single keypress, or I can just leave it hidden and control it entirely through hotkeys.
I now feel crippled using iTunes without this plugin; the things it provides should have been part of iTunes to begin with, and integrate seamlessly once installed. It is the best 5€ I've ever spent, as a shareware registration. So, for any other MacOS X-using friends out there who run iTunes constantly... Synergy is well worth the download. :)