I picked up CoverSutra a little while ago in a bundle purchase, and I generally liked it -- it's an iTunes controller with the added features of regular notifications with album art, a music search, and Last.fm scrobbling. My one complaint with the software was that it was a bit of a CPU hogger -- my little Mac mini chugged right along trying to keep it running, and I occasionally had to turn it off completely if I was doing something else CPU-intensive.
But maybe with newly released version 2.2 they'll have fixed that problem -- not only have they made the app fully compatible with Snow Leopard and iTunes 9, but they've beefed up performance, taking advantage of all available CPU cores and, they say, dramatically loading album artwork and searching music faster. I haven't tried it yet, but if you've had the same problems with CoverSutra I have, it's worth picking up the new version and testing it out. 2.2 is of course a free upgrade to current users, and the app itself is available for $19.95.