In response to my Ajax rants, Mark Finkel points out browsers can do rich graphics using SVG and VML.
Frankly, this is the direction the web needs to head. I am a big fan of these vector graphics formats (my friend Richard See and I launched Visio's SVG efforts).
The problem is neither SVG or VML have ever been fully accepted and supported. The browser wars ended (temporarily) and the two main combatants stepped back from the field just before a vector graphics format was standardized. This has left a gaping hole in web development which Flash has rushed in to fill. If Mozilla does a great SVG implementation, the game may change...but that will something new, call is Ajax-S (Ajax with SVG). The hype and excitement about Ajax is that it runs on what is 99% supported by browsers today.
As an aside, my best friend designed a vector graphics format for the web over 10 years ago, and Mosaic actually was supporting it...just as Netscape tore the browser market away from them.