Do you know that it is possible to download the entire Wikipedia Encyclopedia to your computer and use it offline. Other than static HTML pages, you can also download all the images and photographs from the Wikipedia website in one go.
The full Wikipedia website and the images are available in zipped format that can be extracted using the free 7-zip utility.
Download Wikipedia HTML webpages - Nov 2006 Dump
Download Wikipedia Images - November 2005 Dump
These dumps are intended for private viewing in an intranet or desktop installation - you may not host them on a public website.
Geeks may prefer to download Wikipedia Database Dumps that are vast and have more current information than the static HTML dumps. These are essentially XML files for MediaWiki software that can be imported back in SQL databases using freely available php scripts.
Still, none of the above methods are simple enough for mom. What we need is a Wikipedia DVD set like the one available for Encyclopædia Britannica.
Related: Wikipedia Rel=NoFollow Change
Update: While it is possible to download wikipedia using software like wget or httrack, Wikipedia policies prohibit using web crawlers to download large number of articles from Wikipedia servers.