The name "Bluetooth" is from the 10th century Danish King Harald Blatand - or Harold Bluetooth in English. King Blatand was instrumental in uniting warring factions in parts of what is now Norway, Sweden and Denmark - just as Bluetooth technology is designed to allow collaboration between differing industries such as the computing, mobile phone and automotive markets.
The technology was developed in Sweden, and the special interest group that formed to push the technology decided on this name.