What did Martin Luther contribute?

Martin Luther was one of the key proponents of the Reformation in Germany - which resulted in the Protestant church separating from Catholicism. Basically he became convinced that the Catholic religion of the time had moved away from the truth of The Bible. One of the things he is famous for is asserting that salvation is by grace alone through faith alone.

I suppose that he was that too, but all I was thinking about was the fact that he posted the 95 Theses on the church door of Wittenburg. I have a hunch that they were changes they he believed that the Catholic church need to implement into their way of doing things.