Free GRE online tests

The sites below are free GRE practice tests and are excellent sources to practice GRE. It will make you adapt to the test condition. So practice one test at least a day. It both physically and psychologically prepare for the tests

http://www.4tests.com/exams/examdetail.asp?eid=11

http://www.syvum.com/gre/

http://www.petersons.com/testprep/practice_test.asp?id=1295&sponsor=1&path=gr.pft.gre.