I like non-linear presentation software like prezi. The problem with Prezi is it is not open source and not a desktop client (For linux). You will say use Libra-Office Impress but it is linear and I hate that. If there isn't any non-linear presentation software for linux like Prezi Desktop, than is there a plugin that make Libra-Office Impress like it or Apache OpenOffice? I want a desktop client, and not a web-base app!
[1] Linear Presentations are those presentations in which the flow of the presentation is controlled by the person who is presenting. The concept is frequently employed in multimedia applications and presentations. An example of linear presentation is a pre-recorded movie presentation.
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Have a look at Sozi.
To use Sozi, you first create an SVG file containing everything you want to present in a graphics program of your choice, for example Inkscape. After you've created the presentation image, you open it with Sozi and define your animations.
Sozi will export the presentation in a standalone HTML file, viewable in most modern browsers.
Dizzy is a browser based java script non-linear presentation software. Open source and based on SVGs. Never used it though.
As a warning which you probably don't want. From conferences always the worst presentations are the non-linear ones. The audience tends to end up disorientated, or more interested in the animation than the content. So if you are going to use a non-linear style try to stay away from trying to wow the audience with animation, and wow them with great content.
Going the opposite direction from prezi LaTeX beamer is great once you get used to it. Open-source, and makes you concentrate on good content rather than animation!