Found a Minimum Speed Limit sign in the middle of my town.
I know here in Brazil there's a minimum speed limit on highways of 50% the max, but there are no signs, and it doesn't apply in heavy traffic.
In Denmark we have a single piece of highway were we have a “crawl lane”. It’s slightly uphill and outside the lane you must go at least 80km/h. I know it is more common in Southern Europe.