From Make Magazine:

The Wisconsin Online Resource Center has a great collection of interactive animations for learning the ins-and-outs of electronics theory and application. If you’re a visual learner, like myself, you’re likely to find these ‘learning objects’ very helpful. In addition to basic principals of AC/DC, digital/analog, logic gates, op-amps, motors, they cover pneumatics, hydraulics, sensors, and bunches more.

If you’ve found circuits confusing/intimidating in the past, try poking around a bit in the DC section, start with the basics or just click on something that sounds cool Woohoo – learning is fun!

There has been a lot of work put into this impressive collection of tutorials and resources. I’d recommend this to anyone wanting a basic introduction into any of the topics mentioned above. I particularly enjoyed the hydraulic and pneumatic sections.

Wisconsin Online Resource Center Digital Library