Free Information, Great!
Wikipedia is written collaboratively by an international group of volunteers. So if you ask, whether you can contribute to Wikipedia, the answer is YES. Because anyone with internet access can write and make changes to Wikipedia articles.
Since its creation in 2001, Wikipedia has grown rapidly into one of the largest reference web sites, attracting around 65 million visitors monthly as of 2009.
There are more than 85,000 active contributors working on more than 14,000,000 articles in more than 260 languages.
Find here for your references such as Arts, Biography, Geography, History, Mathematics, Science, Society, Technology and much more.