photo credit: Sandia National Laboratories; image source
The Z-Pinch machine in this photo (hi-res version) at Sandia National Laboratories is a plasma confinement system that discharges a very large voltage through fine wires. For more information, see Sandia Z Accelerator, and to learn about fusion power production, see Fusion Machines at the American Physical Society's outreach website Physics Central. To explore plasma confinement, see FusEdWeb.
PhET: Circuit Simulator
Once you have clicked on the "simulation" link below, be sure to read the Java Security Advisory before running the simulation: To do that, click the "Read now" button on the yellow band near the top of the PhET page.
Try the PhET: Circuit Simulator -- it's fun and quite instructive. You can build circuits with wires, resistors, batteries, bulbs, and switches, in whatever combination you like. Once you have the circuit all built, throw the switch, and you can make voltage and current measurements anywhere in the circuit.
(This feature was updated on July 8, 2013.)