(Thanks Pota for the novel and the video )
I am just finishing up with Neal Stephenson's Cryptonomicon (don't bother trying to read an e-book version, its some 1000 odd pages). The novel is really nice, but the nicest part of it was Van Eck phreaking. On any CRT monitor, the electron beam is moved around by coils which produce an electromagnetic field. Now, for the coils to 'direct' the beam, the current supplied to them should vary in time in such a way that the effect of the coils' magnetic fields deflects the beam to where it is required. Voila! Currents changing in a conductor automatically mean electromagnetic waves being transmitted into space. You might not think these are strong enough to be picked up, and neither did I till The Pota fished out a youtube video, showing it happening ! The wiki article points at one with a more... practical bent, of compromising electronic voting machines !
Ah, I can imagine Mr. Van Eck ( or the TEMPEST fellows) on a lazy afternoon, gazing into the blue sky, thinking about that inordinate din the TV was making, and FLASH ! Coils, changing currents, phreaking !! Phew, awesome !