Sites that offer general information about common tests, test-preparation courses, and testing resources are: 

http://petersons.com/

http://princetonreview.com/

www.actstudent.org/

http://www.collegeboard.com/;

http://www.ets.org/

http://www.fairtest.org/

http://www.kaptest.com/

There are many more sites that address test and test preparation as well as many books that do the same.