"new" music found... right where I left it

I just KNEW there was more music in my iPod than I was hearing! Despite clearly setting preferences to be as random as possible, I kept hearing the same songs over and over. So I made a new Smart Playlist which contains only songs which haven't been played in the last two weeks, and it auto-updates every time I sync my iPod.

Now I'm hearing the other half of my library. Woooooot!