Sites

Simple Harmonic Motion (Popularity: )
http://www.physics.uoguelph.ca/tutorials/shm/Q.shm.html
A series of graphical animations illustrating the features of this phenomenon, with online consolidation exercises.

Damped Harmonic Motion (Popularity: )
http://musr.physics.ubc.ca/~jess/hr/skept/SHM/node7.html
Mathematical Equations of Damped Harmonic Motion.

Coupled Oscillations (Popularity: )
http://lectureonline.cl.msu.edu/~mmp/applist/coupled/osc2.htm
This applet illustrates coupled oscillations of a linear chain of identical noninteracting bodies connected to each other and to fixed endpoints by identical ideal springs. All bodies start from rest, ...