That's my awesome Bobrik
Can't live without it.
http://www.adteknik.se/swedish/bobrik.htm
Doesn't look like that page is available in English (for you non-Swedes) but it is an advanced version of this thing:
http://www.adteknik.se/english/activeGPS.htm
The Bobrik shows your speed, the speed limit and warns when you are getting nearby a speeding camera.