Wikipedia has a new capability to create books out of articles. For example, a friend is on a trip this week to the Holy Land. Based on her itinerary, I created a collection of articles that I thought might be relevant as background for her.
It’s quick and easy to do; you turn on the book creator function and then add links to your book.
There’s an option to export to .pdf, Open Office format (.odt), and even to a physical book publisher for a fee. My book, which took only a few minutes to create, clocked in at over 500 pages and would have spanned two physical volumes. I don’t think it’s worth it for the printed version — mine would have cost more than $50 — but for something like a Kindle or a netbook, an easy-to-read .pdf version would be a useful reference to have, I think.