Finding the Serial Number Without iTunes
Your Mac keeps a record of all iPods it connects to. I mean, it must to remember which ones to automatically sync and which ones not to, right? The file can be found at:
Macintosh HD > Users -> [your user name] -> Library -> Preferences -> com.apple.iPod.plist
If you open the file in TextEdit or something it might get messy. Just do the quick view by pressing spacebar and you should see lots of stuff that looks like this:
Look for the line after "< key > Serial Number < /key > ", and it should look like this:
example: < string > G8312CO150D4 < /string >
And that, my friends, is your serial number. There will be a separate entry for every iPod you've connected so if you own more than one, keep looking until you find the one that doesn't match the ones you have.
Not sure if this will ever actually help anyone recover a lost device, but happy hunting!