WOW -- If you use iTunes, and especially if you use Last.FM too, check this out. It does a bunch of little things, it does them very very well and it otherwise stays out of your way:
- Puts a little picture of the current cover art on the desktop (whence the name, I suppose). This is fun but, for me, the least of the appeal.
- Excellent Last.FM integration without being iScrobbler (too minimal) or last.fm desktop (fuck off).
- A beautiful HUD window for quickly doing play/pause/next or just "what song is this" ... that pops up instantly (most other programs pop up almost instantly, which is almost not annoying).
- A fast, well-designed search right from the menubar that beats iTunes' search.
- Growl notification
- Keyboard whammy-key setup that's easy and straightforward.
I mapped most of the CoverSutra keys off of F6 (following their defaults), then took some of the special doohickey keys around the edge of my keyboard and used my keyboard's preference pane to map them to the same F6+whammy keystrokes. Now if I hit the "music" button I get the little mini-console; "find" gets me "search all" while ^-find gets me "search artists".
If I haven't pimped it before, I also enjoy the Harmonic dashboard widget -- it sits in your dashboard, and as iTunes plays each song hunts for lyrics. If it gets a strong match (and no lyrics are present) it stuffs them in. You may occasionally hear the song 'hitch' for a fraction of a second, but this is less annoying than you'd think. Mostly, you can just ignore its presence -- and just happily notice the extra metadata when the song comes across your iPod.