SAT/College Board (Information and registration for the SAT. Information about the PSAT test for Juniors.) http://www.collegeboard.com
ACT (Information and registration for the ACT. Information for the PLAN test for Sophomores.) http://www.act.org
An article from NPR that addresses taking the SAT versus the ACT http://www.npr.org/templates/story/story.php?storyId=7495614