There's a kokyu-nage our system calls the "20 Year Technique". It is called this because we have been taught that it takes 20 years to master it. I think they are being optimistic.
Here's a link to an article by Sensei Suenaka at FightingArts.com. It describes the technique as it is performed from a shomen-uchi attack.
I'll be working on this technique for as long I can continue to practice Aikido.