In the past Vernier used to develop computer simulation software. In the past 10 years we have gotten away from that type of product and concentrated on sensors, software and curriculum to facilitate real-world data collection in the classroom. There are many sources available. You might want to check out the following options:

A good list of free physics simulations is available at:
http://prettygoodphysics.wikispaces.com/PGP+Simulation+Links

“Interactive Physics”
http://www.design-simulation.com/ip/index.php

“Physics Education Technology (PhET)”
produces fun, interactive simulations of physical phenomena. More than 35 simulations let students experiment with circuits, string tension, kinetic and potential energy, radio waves and electromagnetic fields, balloons and static electricity, ideal gas and buoyancy, velocity and acceleration, sound waves and the Doppler effect, and more. (NSF)
http://www.colorado.edu/physics/phet/

“Explore Learning”
Explore Learning is an education company that sells “gizmos” to simulate different scientific phenomena.
http://www.explorelearning.com/index.html

“Physics to Go”
Physics to Go is a collection of reviewed resources for teaching and learning about astronomy, electricity and magnetism, fluids, light, modern physics, motion and energy, quantum physics, and waves and pendula. (NSF)
http://www.compadre.org/informal/index.cfm

“21st Century Explorer”
answers questions that include: Why do we want to travel to Mars? How would your body change in space? Where would a space explorer find water and oxygen? How can we travel faster in space? Student actors (on video) and hands-on activities are featured with each answer. The site is for Grades 3-5 and available in Spanish. (NASA)
http://ksnn.larc.nasa.gov/21Century/index2.html

“Calendars Through the Ages”
looks at the astronomical basis of calendars, the history of our calendar, and when various countries moved from the Julian to the Gregorian calendar. Learn about Leap Year, the solar cycle, equinoxes and solstices. (NIST)
http://www.webexhibits.org/calendars/

“Genetic Basics”
looks at how genes work, exceptions to Mendel’s rules, how DNA gets replicated, genes and disease, current research and recent discoveries, and how applications of genetic research (biotechnology) are being used in agriculture, health, and medicine to change our world for the better. (NIH)
http://publications.nigms.nih.gov/genetics/

“Genetic Science Learning Center”
features animations and activities for learning about DNA, cells, and other topics in genetics and bioscience. Build a DNA molecule. Transcribe and translate a gene. See why a firefly’s tail glows. Use DNA evidence to solve a mystery. Extract DNA from wheat germ and see real DNA. Find out how genetics are being used to save endangered species. Learn about stem cells, addiction, gene therapy, cloning, and genetically modified food. (NIH) http://gslc.genetics.utah.edu/

“NASA Kids’ Club”
features interactive games (for Grades K-4) on the solar system, rockets, addition, “guess what number I’m thinking of,” and NASA spinoffs (everyday items developed from NASA research). A teachers’ area links to guides for teaching about clouds, precipitation, energy, winds, weather, planetary geology, flight, the Wright brothers, rockets, the electromagnetic spectrum, and careers. (NASA) http://www.nasa.gov/kidsclub

“Way to Go, Einstein”
is a fun introduction to the thinking of a man who influenced all modern scientists. Learn about Einstein’s revolutionary conceptions of space and time, light, matter, and energy. Answer brain-bending questions about how the world works. Find out about every day applications of his work. (SI)
http://ology.amnh.org/einstein/index.html