"ChatGuest1" sent the readers of Defending the Earth! to the page about Vitex on the Cybus Industries website to look for the number for that day's "special frequency or wavelength"; the number turned out to be hidden in plain sight on the Cybus Fitness website, which had been advertised on the Cybus website. (GAME: Cybus Spy)
The Tandocca Scale was a series of wavelengths used as a carrier signals by migrant bees. (TV: The Stolen Earth)
Lupine Wavelength Haemovariform's were trigged to transform by specific wavelengths from the lights of moons. (TV: Tooth and Claw [+]Russell T Davies, Doctor Who series 2 (BBC One, 2006).)
The 456 used a wavelength which they were named after. (TV: Children of Earth: Day Three [+]Russell T Davies and James Moran, Torchwood series 3 (BBC One, 2009).)