Here is a site that PSAT Math prep. Create a trial for free. Great videos!
Here is some quizlet PSAT Math Tips.
Here is a site with some free PSAT practice tests.
Here is an overview of the PSAT Math section.
Here is the College Board's overview of the math tests.
Here is a set of College Board math questions for practice without a calculator.
Here is a set of College Board math questions for practice WITH a calculator.
Here is another set of PSAT practice math questions.
This site has some extensive details on the PSAT math section.
Here is a link to the live Khan Academy lesson on PSAT Math.
More SAT math from Khan Academy.