This applet helps the student investigate functions with 3 parameters A, B, C, and what a certain change in the parameter would do to the graph.

This site has 5 different applets to investigate functions.

This applet helps the student find the domain of a function.

This site has several applets for several kinds of functions such as the exponential, piecewise, odd, even, and periodic functions.

This helps with graphing functions.