I would like to make (simple) mathematical presentations using mathjax. Most importantly I want to be able to let text show up step by step. Does anybody here know a program that would allow me to do this without too much hazzle ?
I'm afraid that this is not the right place to ask this, but as I think other mathematicians may find this question also interesting, I hope it is ok to ask it here.

It sounds to me that you want one of the ways of integrating latex into powerpoint. I've heard good things about iguanatex, which is free and would do the job. I should note that $\LaTeX$ actually has a presentation-type documentclass, called 'beamer.' You can read more about that here.