Bluetooth

Ericsson, the Swedish multinational tech company created the Bluetooth logo by adapting the runes for the name of the Danish King Harald Blatand  (Blåtand/Blåtann) 935 - 985 C.E.

Legend reports King Harald was nicknamed "Bluetooth" for his love of blueberries which stained his teeth.
He is best known for uniting Danish tribes and as an early convert to Christianity around 960 C.E

Bluetooth technology enables wireless communication between computers, printers, cellulars and other devices.