I have posted this in the discovery based learning section of Radian Measures of the Sinusoidal Functions Unit.  If anyone uses this and creates an investigation would you please be willing to share. 

1.  Visualizing Radian Measure -- Click here to link to Ted Coe's Unwrapping A Circle Applet [T], [V]

This is a tool to help students envision the meaning of "radian" by thinking in terms of radius-lengths.