CrispyTunes.com

Do you wish you have Wikipedia with you 24/7 regardless of internet access? Fret no more, you can easily download (Win) Wikipedia onto your iPod with Encyclopodia.
Every iPod is supported except the 5th generation iPods (color iPods). You can choose to install multiple encyclopedias or just one. Encyclopodia will work with iPodLinux, so no worries there.

from http://www.mactips.org/archives/category/ipod-tips/page/2/