Asura Cryin', Iron Man Recommendations
Both Anime have a form of Mecha in them. Not to mention, they have interesting power sources for the Mecha... Tony's suit is powered by the arc, and the Mecha in the other Anime are powered by... shan't spoil it. :)
But the series is based around a secret as well that I can't give away, and it keeps you on your seet.