Presenting data is an extremely fussy business, where you'll be tweaking and altering it often. Once a middle-manager sees a chart, it is just about mandatory that they have to add their own, uh, mark of excellence. These changes are often completely irrelevant, but it's self-defeating to deny them this luxury in many cases. "Yeah, and get rid of that font. I like Tahoma."

So the priority is on making it bone-simple and quick to incorporate presentation and style changes.

I would also recommend HTML, using the minimum of machine-generated graphics. PDF is *usually* too cumbersome to author and revise. SVG is worse, but only because it's so nascent that the available tools are weak. I wouldn't rule them out, except that they also raise the complexity of ensuring your audience is configured to view them properly. Everyone can view paper, and everyone who is anyone can view HTML.

In those cases where the machine-generated graphics are important, use the method which takes tabular data and creates the basic plots as distinct graphics files. In a quickly configurable way, if you have too many middle-managers.