TOEFL:
http://www.examenglish.com/
http://www.stuff.co.uk/toefl.htm
http://www.learn4good.com/languages/toefl/structure_smpl_sntc2.htm
http://www.gettoefl.com/practice.htm
IELTS:
http://www.examenglish.com/
http://www.canadavisa.com/ielts/free-practice-tests.html
http://www.testpreppractice.net/IELTS/Free-Online-IELTS-Practice-Tests.aspx
SAT:
http://www.princetonreview.com/college/_free-sat-practice-test.aspx
http://www.proprofs.com/sat/exams/practice-tests.shtml
http://www.testprepreview.com/sat_practice.htm
GMAT:
http://www.princetonreview.com/business/free-gmat-practice-test.aspx
http://www.800score.com/gmat-home.html
http://www.veritasprep.com/free-gmat-practice-test/
GRE:
http://www.princetonreview.com/grad/free-gre-practice-test.aspx
http://www.testpreppractice.net/GRE/Free-Online-GRE-Practice-Tests.aspx
http://www.800score.com/gre-index.html
