As a wikipedia writer, I can confirm that it can be a good resource for astronomy. This "book" feature was implemented on en.wiki at least 1 year ago, and it's now available on all major wikis, including german wikipedia, french wikipedia and italian wikipedia. A book is a collection of wikipedia articles that follows a common matter/instruction. I will press to create some new books and to increase the quality of already existing ones, anyway some other astronomy books are available here:
http://en.wikipedia.org/wiki/Categor...s_on_astronomy.
I write mostly on it.wiki, where I'm describing all star formation regions of Milky Way. Unfortunately my articles are in italian, and google translate provides a bad translation of astronomical articles... May be in future I will think to translate by myself some of my works.