Leopard makes it really easy to create some useful scripts. In just a minute or two, I cobbled together this script. When you run it, it gives you a box to paste any amount of text into. Hit "OK" and "Alex" will read and record the text, place it into a new playlist in iTunes and add a numbered extension to the file. Do this for each chapter in a book then upload it to your iPod.
It's a simple automator script you can get Here.