Boron Aluminium Magnesium is the slipperiest material known to man, it is also nearly as hard as diamond. Wheel bearings using a BAM coating could measurably reduce rolling resistance and increase the life of bearings.
I wonder if any thrust bearings with BAM coatings are already used in consumer applications. I also wonder if BAM coating companies have bearing demonstrations.
Another interesting coating is Diamond Like Coating. From what I can tell DLC is more common and is even used in high performance car engines today but isn't as slippery as BAM. DLC also has excellent wear characteristics.