Bluetooth is a wireless technology standard for exchanging data over short distances using radio waves.  The technology was created by the Swedish telecom company Ericsson in 1994, and is named after the tenth-century Danish king Harald I, nicknamed Harald Blåtand (“Blue tooth” in English).  An Ericsson employee was reading The Long Ships at the time – an historical novel about the Vikings and King Harald Bluetooth.  The king is credited with uniting independent Danish tribes into one kingdom – as Bluetooth technology united wireless communication protocols into one universal standard.  The Bluetooth logo is a Viking-era rune, combining the letters ‘H’ and ‘B’ for “Harald Bluetooth.”  Read more on Wikipedia.