Geogebra
Applet Description
Sine Function Transformation My very first applet!!! Go Geogebra!
Solids and Volumes of Revolution This thing is awesome!!! I wish I had it when I was in Calc III. It allows you to choose a function and then it graphs it in three dimensions for you to inspect.
Polar Coordinates This applet lets you plot graphs using polar coordinates
Rotation of the Earth This applet models the rotation and revolutions of the Earth with focuses on how the sun shines on it.
Peano's Curve Shows the different steps necessary in drawing Peano's curve. Kind of pretty
Trig Functions This applet is used to discover the relationships between the six trig funtions.

Here are some of the Applets I have designed on Geogebra
Conics Applet

Binomial Distribution Applet

Riemann Sums

Sin, Cos, and the Unit Circle!

It's the Golden Ratio

Rectangular and Polar Coordinates