Plasma
This looks like a fun kit for $64, make plasma balls, light up fluorescent tubes, make sparks… – “Solid state high voltage power supply is perfect for high voltage experiments, like Kirlian photography. The high voltage at the terminal won’t electrocute you, so its relatively safe, but it can burn you, so use caution. Can be run from 5-24 VDC so the output voltage can be directly adjustable.” – [via] Link.