Prosper
Prosper is a LaTeX class for writing transparencies, and maybe making presentations for use with Acrobat Reader. The only thing that it's got going for it is that it's really minimal.
I used to use it a lot before I discovered Beamer. I created my own style-files, which you can get from the links in the bar to the right of this page.
Here's a screenshot.
You're probably better off using Beamer.