Today: tools for actually delivering a PDF presentation (I make them with rst2pdf ).
One of the smartest things we can do for one another as speakers (even occasional ones!) is put a PDF presentation tool on our laptops. Every presentation tool should be able to save as PDF - and if someone has a PDF presentation tool on their machine? You're saved :)
For mac: try Présentation.app a Python script that gives a fully-featured speaker view with speaker notes, timer, next slide, etc.
For linux: try PDF Presenter Console. Ubuntu users can install from apt, and again, it supports speaker view, next slide, notes, timer, etc. It's also an active open source project, so you can always fix something if you need to.
Both tools have similar features to what you'd expect from Powerpoint/Keynote/Impress, and I personally find them more than adequate for my needs. If you have other recommendations (especially for Windows, which I don't have suggestions for) then please share in the comments, I would love to know of more excellent PDF tools!