A fascinating Midrash relates that in the end of days, after the dead will arise from their graves, G-d will sit in Gan Eden, paradise, and teach Torah.
The righteous will be sitting before Him, listening,  all the angels and heavenly beings will be standing at G-d's right side, the sun, moon and stars at His left side.
G-d will reveal new Torah, never taught before.
(The Torah will never change; new parts will be added, and the original will stay) After the Law, G-d will teach moral precepts, and then Zerubbabel will arise and recite the Kaddish.
His voice will travel across the world, eventually reaching the sinners in Hell.
As all will be answering "Amen", those sinners will answer "Amen" too, from deep inside Gehenna.
Their voices will reach G-d Almighty, who will ask "What are these voices I hear?" The angels will say "These are the sinners in Hell who are answering "Amen" too.
Immediately G-d will feel tremendous mercy on them.
He will "Why should these unfortunates suffer any more.
They have suffered enough, in the time they have already served in Gehenna".
He will take out the keys to Hell in front of the entire assembly, and hand them to the arch-angels Gabriel and Michael and say to them "Open the doors, and take these souls out of Hell, for they are the keepers of "Amen" - even within hell they answer "Amen" Immediately the angels take those keys and open the forty thousand doors of Gehenna and release these souls from purgatory.
In the end of time, the merit of answering Amen will be what pulls them through.
I think this story underscores and emphasizes the unique position and power that Amen and the Kaddish holds in Jewish thought.
Let us take heart next time we hear the Kaddish recited, and answer Amen with soul!