I gave a talk last week at Camp DevOps about Ansible and EC2. The talk is written in present format, which is a very lightly marked up text format, similar to Markdown. You can see the source file in a Github repo.
It was liberating to focus entirely on content and not worry too much about the exact appearance of the slide.
I also went for a minimalistic approach where I often didn’t even use titles. The slides won’t make much sense if you just look at them without me talking. Hopefully, they made some sense when I was talking in front of them.