This site is an excellent resource for anyone studying calculus. The visualization of some of the material makes learning much easier for someone who might have a hard time "getting it."

Excerpts from site:

Originally, this collection was designed for instructors to give some ideas how technology, in particular, computers, can be used in the teaching of calculus. Detailed instructions on implementing these ideas with various public domain, shareware and commercial software packages are provided. The collection has been expanded to include tutorials, interactive modules (LiveMath, Java, and Javascript) which can be used by either students or faculty and includes detailed instructions for TI-85 and TI-86 graphing calculators. As an additional aid for students, modules containing quizzes and drill problems have also been added.