This will show a liltte bar with the remaing time of your Judgements, if you hit the target it will be reseted.

Installation:
Follow the instrutions in your chat screen (you have to open your talent tree)

Limitation:
Won't work is two pallys cast the same Judgement on a mob.
Won't work if there are multiple mobs around with the same name.
There are some bugs in WoW again, making the addon not working correctly sometimes.

You can move the bar around while holding the shift key.