Calculus

Calculus-Help.com - Features a new practice calculus problem every week with complete solutions. Includes an archive of prior weeks' problems and solutions.
http://www.calculus-help.com/

Calculus Survival Guide - Offers helpful tips on taking tests and keeping up with the class. Geared toward university students, but also applies to high school.
http://galileo.math.siu.edu/~msulliva/Courses/150/S06/survival.html

A History of the Calculus - The main ideas of calculus developed over a very long period of time. Read about some of the mathematicians who contributed to this field of mathematics.
http://www-history.mcs.st-andrews.ac.uk/HistTopics/The_rise_of_calculus.html

Karl's Calculus Tutor - Introductory information on counting numbers, integers, limits, and derivatives.
http://www.karlscalculus.org/

Visual Calculus - Short descriptions and examples for limits, derivatives, and integrals. Various plug-ins are needed to view some of the pages.
http://archives.math.utk.edu/visual.calculus/

Calculus Made Easier - An introduction to the basic concepts. The derivative and integral are explained. Resource links included.
http://www.wtv-zone.com/Angelaruth49/Calculus.html

Algebra and Calculus Sketches - For calculus, gives the tangent line problem and its solution.
http://www.mathforum.org/sum95/ruth/sketches/algcalc.sketches.html

Automatic Calculus Solutions - Check calculus homework. Enter a function and click for a step-by-step derivative or integral with each step explained.
http://www.calc101.com/