The fifth generation iPod with video currently has 11 games available for purchase from the iTunes Store, including a brick-bashing game called Vortex. If the description and image aren't enough to help you decide whether or not to spend $4.99 on Vortex, Apple has released a free, playable demo of the game that includes two levels from the full version.
iTunes is available as a free download from http://www.apple.com/itunes. If you already have iTunes, you can grab the free demo (a 22.6 MB download here. iPod games can only be played on fifth-generation iPods, and they can't be used within iTunes or on an iPod nano or AppleTV (or Zune!).