Iron Man was powered by Lego. The Tumblr "Source Code in Television and Films" by John Graham-Cumming has exposed the programming code Tony Stark used to bring the Iron Man suit to life. You'll never guess it but it is code for a Lego computer.

The Internet Movie Database confirmed this:
The code that appears on the computer screen at 34 minutes into the movie is a utility that downloads firmware into Lego robotic toy (called RCX). It may suggest that Tony Stark used this program to download firmware into his robotic suit. [IMDb]
Graham-Cumming is a real-life programmer. He hunts down the source codes that are featured in movies. Incredible finding, isn't it?