Sociology

http://en.wikipedia.org/wiki/Sociology

These site is very useful because gives you the definition and the history of Sociology, besides it gives you some useful bibliography and a lot of good links about sociological associations around the globe and some others with many tools like journals of sociology and many directories of sociological resourses

http://www.sociology.org/

These is a really good site, it has a lot of articles about many many topics of sociology whritten by diferent autors. Besides you can know how sociological knowledge advances, 'cause it gives you current information.