PowerPoint pretty much sucks, for a variety of reasons. And in that group I also include OpenOffice.org Impress (which I personally choose to suffer through) and Apple's Keynote. They all just suck in different ways. Being a Web dude, I've always looked for a web-based solution, and now there appears to be two contenders: Dave Raggett's Slidy (he's the guy who invented the awesome Tidy, so you know he's a smart cookie) and Eric Meyer's (we all must bow to him & his CSS godly knowledge) S5, which stands for Simple Standards-Based Slide Show System.
Both are good, & both work the same: they provide you with the CSS files (which you can customize ... & which you should customize, so your templates are unique) and JavaScript, & your job is put your entire presentation in an XHTML file. If you know HTML, this will be easy; if you don't ... well, there's always Impress! Based on my experimentation with both, I'm going to use S5. It supports font scaling a bit better, & it has some features that Slidy doesn't have, especially in the footer that's auto-generated on every slide. On top of that, Eric Meyer, showing his background as a writer, has better documentation that Dave Raggett, which is key. But in either case, both Slidy & S5 are worth exploring, & it's great news that we finally have an alternative to PowerPoint and the other presentation clients.
(Check out all of our posts on presentations, OpenOffice.org, S5, and Eric Meyer.)
