Left: Nuclear Physcis Simulation...............................Right: Quantum Wave Interference Simulation
(Images are from the PhET website.)
The PhET website from the University of Colorado is the best source of computer simulations in physics. In particular, they have a wide assortment of quantum mechanics simulations. These are not just simple animations. They are very rich simulations that allow the students to explore and take measurements as they would in an experiment. You can use these simulations online or download them onto your computer.
The simulations are really easy to use and they tend to follow a similar format. Most of them also have lessons associated with them. I haven't found any yet that I felt I could use with my class, but they are useful for getting ideas of how to use them. In addition, the ones designed for use with university students gave me a deeper understanding of some of the topics. I have posted two of my lessons there so far: for Electron Interference I used Quantum Wave Interference and for Radioactivity and Intrinsic Randomness I used Alpha Decay .
If you develop a lesson plan using these simulations, don't forget to post them for others. Also, please donate to PhEt and fill in survey forms so they can keep going.