Forget about that meeting you have in 10 minutes to present your new idea? If you need to crank out a presentation really quickly, Biggie is a tool that lets you create and publish a slideshow within minutes.
Biggie uses Markdown to make the process of creating a slideshow easy. From Biggie, just type in what you want on each slide, use Markdown to format it, and click "publish" when you're done. That's it. Obviously you can't create fancy animations, but if you're in a pinch and need a presentation quickly, Biggie does the job.