Erbium (atomic no. 68) brings you Dancing With the Stars. Really.
The element is essential in fiber-optic telecommunication cables, which bring cable television and Internet to your homes and apartments.
According to the US Geological Survey, "fiber-optic cables can transmit signals over long distances because they incorporate periodically spaced lengths of erbium-doped fiber that function as laser amplifiers. Er is used in these laser repeaters, despite its high cost (approximately $700/kg), because it alone possesses the required optical properties."