Lately, I have been making my presentation slides with LaTeX beamer. I use SVGs created with inkscape (and my handy wacom tablet) for most diagrams and the minted package (which eventually calls pygments) for syntax highlighted source code listings. This combination works well and produces very nice PDFs that I can present with evince.
Unfortunately, the compile time for a large presentation is excessive and makes incremental updates a bit of a pain. It is also wasteful since I am not using many of the good things that TeX provides (I try to minimize my reliance on bulleted lists and math in slides). Many of my slides are just SVG diagrams converted to PDFs.
I remember using s5 once in undergrad. It works but isn’t particularly impressive. prezi is really neat, but it requires using some web-based editor and is based on flash, which make it obviously a no-go. impress.js produces very nice results. It takes a different approach from a slide-based presentation; your entire presentation lives in a big poster and the viewport zooms around to different sections, subject to various scaling and rotation transformations. The effect is very slick, but distracts somewhat from the content. I don’t think it is particularly suitable for any technical content. It would probably go over well for some kind of sales fluff-piece presentation, though. The additional effort of manually arranging each slide in the plane of the poster is also a bit more than I would want to deal with.
I have to see how it performs at presentation time, but it seems to be perfectly acceptable. Now I have to try it with a more complex presentation.