Apple has apparently included a surprise in their latest iTunes updates. Whenever a fresh iPod is inserted into the computer, you are asked to register it and name it. Even if you choose not to register, though, the iTMS opens up to a page that offers a free download of 16 songs!
Now, the hidden, bonus part is this. Even if your iPod isn't new, you can still get this song collection by simply using the iPod Updater (which can be downloaded through the Apple web site [2005-03-23 updater] or Software Update) to restore your iPod. This wipes your iPod's settings, and when you plug in next, the iTunes free music page pops up. (This is how I discovered it.)
Unfortunately, these aren't "16 songs of your choice." The current incarnation of this is 16 "Pop" sounds by Atlantic Records. I assume that because it refers to "Atlantic/Lava Edition," there may be more of these free albums.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050411201442267