It's probably a well documented feature of iTunes since 8.1 but in Cover Flow mode, you can drag the image
of an album to, say, the Desktop (or whatever folder) and it will copy the tracks in that location.
Neat!
[crarko adds: I tested this, and it works as described. You may want to first create a folder on your desktop to drag these into, since this process does not. ]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20090320173912858