Weather radar
Regarding the inadequacies of weather radar in detecting many hazardous conditions there has been a lot of promising recent research using LIDAR.
Meteorologists are very pleased with the ability to better detect convective conditions but this is cutting edge stuff so likely to be many years away from routine use in aviation.
Maybe this will replace our current weather radars in the future. OTOH having a scanning laser on the nose of every airliner may prove to be too hazardous.