Wikibooks, an open-content textbook collection
Wikibooks is a Wikimedia project for collaboratively writing textbooks and related non-fiction books about a variety of subjects.
Although this project is still small, it probably won't be for long. The sister project Wikipedia has experienced tremendous growth within a short period of time! There are three things you can do on Wikibooks. You can read them, you can edit them, and you can write your own content.
To create a user account, visit Special:Userlogin.
Reading is simple. Go to the main page, find a Wikibook that looks interesting, and start exploring. There's also a search box at the top of every page.
Anyone can edit pages in Wikibooks. You don't need special credentials, and you don't even need to be logged in. You might find this a bit scary! See Wikipedia:Replies to common objections for an explanation of why the system still works.
Editing the existing set of knowledge is great, but we'd like you to contribute your knowledge too. You can start a brand new module, or find an existing module and add an entirely new section to it. Don't worry too much about making mistakes - if you do get something slightly wrong, then you, or anyone else, can always fix it later.
Wikibooks and Science
You can find a lots of material related to science:
-Biology: a copy of the cell biology textbook started by Mark Dalton on the University of Minnesota website. http://en.wikibooks.org/wiki/Cell_Biology
-Maths: study of Abstract algebra: http://en.wikibooks.org/wiki/Linear_algebra
-Medicine: material on internal medicine: http://en.wikibooks.org/wiki/Internal_Medicine
-Ecology: a guide to the study of ecosystems: http://en.wikibooks.org/wiki/Ecology
GNU Free Documentation License
If you don't want your writing to be edited mercilessly and redistributed at will, then don't submit it. All contributions to Wikibooks are considered to be released under the GNU Free Documentation License (GFDL). The GFDL ensures that Wikibooks will remain freely distributable forever.