A feature of audio books from Apple (and Audible) is that iTunes will remember where you are in the song/book/etc. Now Apple has added this ability to any song, music, or file of any type in iTunes.
Pick a song, or movie you want to have iTunes remember the position of, and press Command-I (Get Info). In the Options tab, enable 'Remember Playback Position,' and you are done. If you listen to the track, stop and come back to it later, it will continue where you left off. This property is also synchronized with your iPod! Finally, my non-Audible audio books can be used properly, and this even works with videos!
[robg adds: This is well-documented in the iTunes release notes, but given that it's now been submitted quite a few times, I thought I'd go ahead an publish it, in case some of you may have missed it.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20051204114910490