I actually don't know of any app that does what CoverSutra does that does it for free. There are numerous that do something kind of similar to CoverSutra -- like
ByteController (for controlling iTunes) +
Growl (to display artwork) and a slew of others -- but none of them will display the artwork as beautifully as CoverSutra does.
CoverSutra is nice, but if you don't mind not having that silly floating window, and you don't want to pay, just get the following:
1. The Yahoo! Widget Engine (free, and with thousands of widgets, many of which are quite beautiful and useful)
2.
This widget for displaying the artwork in a jewel case...
3. And my personal favorite and the only iTunes controller I will ever use,
iMote. Coupled with Growl notifications, it's really quite nice. Really iMote could be replaced with any other iTunes controller that supports hotkeys but it's the only one I know of that supports Growl. I use the "Music Video" display type, and it's beautiful. Hit Ctrl-Right for next song, and a little music-video type scroller with artwork slides up from the bottom of the screen, announcing all the informaiton, and then it slides back down within a few seconds. Don't need anything else. Oh yeah, and it's free. See attached file.
Edit: Interesting tidbit, the Chinese government blocks the CoverSutra site, probably because it has the word "sutra" in it?
Edit 2: Okay I was wrong, since
http://www.kamasutra.com works. O_O Weird.