This site offers five complete PSAT online practice tests with explanations for every question. You'll also find problem-solving videos and other PSAT prep materials like tips, strategies, and how-to's. The best part? There's no sign-up or sign-in. The PSAT is very similar to the SAT, so don't hesitate to check this website out!

The Princeton Review offers both in-person and online practice SAT exams for free. After the test, you receive a detailed performance report with personalized tips on how to improve your score.

Test Prep Review offers practice for many different standardized tests. This site allows you to quiz yourself on SAT sections, as well as pick and choose which types of problems you would like to hone your skills on

CollegeBoard offers a Question of the day, Sample Questions, Tutorials and Practice Tests for fthe SAT.  

Khan Academy has full-length SAT practice tests available and offer free, personalized practice based on your diagnostic test results!  You can also find booklets, videos, etc. on their website. No login required.