I gave a short presentation to a group of clinical researchers back in November 2012 on technologies and tools that might suit freelancers. I've updated it and have included it here (download PDF, 9.7 MB).
The PDF includes hyperlinks to most of the resources and software mentioned (just click the product name).
If anyone is curious, I used a new application called Deckset when doing the update to the presentation. It was originally written in Keynote, Apple's version of PowerPoint.
It converts plain text, styled in Markdown, and your selected images into nice looking slides. There are no fancy animations or transitions, just neat typography and a simple style. It's forcing me to keep my messaging as clean as possible.