clipped from: kempele.fi 
Here's a program that will semi-automatically download album cover images for your music collection. All you have to do is point it at the root of your music directory and for each directory, the program will download a set of corresponding (well, best guess) album covers from the Internet, from which you can choose one that suits your fancy.
Currently supported image providers:
Check out the tutorial to get started.
The cover images are in one or more of the following places: