Markus Kuhn (rhymes with "moon"). This is the personal page of the smartest person in the world, bar Stephen Hawking. I particularly recommend that anyone wishing to develop better hardware read his thesis on eavesdropping risks of computer displays.
The Anti-Tempest Computer Project: These guys are designing their own Tempest (Tempest is the prevention of van Eck Phreaking, so their name is something of a misnomer) approved monitors, I think. They also have some nice links to other resources.
Tempest for Eliza: This is basically the opposite of van Eck Phreaking: instead of trying to spy on the monitor, it uses the monitor to transmit a message (in this case a song) over the radio. It works a lot better than eckbox (and doesn't require an infamous ADC) and it will surely amuse you while you struggle for breath amid the clouds of melting solder fumes.
Wim van Eck's original paper on the subject of Electromagnetic Radiation from Video Display Units: An Eavesdropping Risk?
Tinfoil Hat Linux: A security-oriented distribution of linux featuring the use of Soft Tempest (software that foils van eck phreaking stuff). It is very useful if the Illuminati are watching your computer, and you need to use morse code to blink out your PGP messages on the numlock key. In fact, it comes with a program that allows you to do just that.
US Laws regarding van Eck and other eavesdropping devices. We are serious when we say that Eckbox is (currently) mostly a proof of concept, and will only ever be intended for testing and development of Tempest materials and software. Don't make the NSA hunt you down.