I didn't make these programs but I use them in my college physics classes. Maybe for someone that has not got enough background in circuits, these programs can be useful. Here is a link:
PHET is supported by a few sources include the National Science Foundation and has a number of good simulations for math and science.
I will be adding some tutorials on simple circuits with these demonstrations to my blog (liudr.wordpress.com).
I especially like the circuit construction kit. http://phet.colorado.edu/en/simulation/circuit-construction-kit-dc
They even took the time to make the resistor color code work!