Is there a section on Khan Academy to prepare for the accuplacer?

According to this article I found on the College Board regarding the ACCUPLACER College Level Math, the five types of math you will be experiencing on the test are:

• Algebraic Operations
• Solutions of Equations and Inequalities
• Coordinate Geometry 
• Applications and other algebra topics
• Functions and Trigonometry

The website explains some of the topics that are in the 5 different types of math. I believe almost all of these topics can be found in the Algebra 1 and Algebra 2 courses on Khan Academy(mostly all can be found under Algebra 2). You could brush up trigonometric functions, exponential functions, logarithmic functions, conics, complex numbers, factoring and expanding polynomials through the Algebra 2 course.

You could also brush up on other graphs of algebraic functions and systems of equations through Algebra 1.