perspective projection
Up to this point, if you need a perspective projection of a raster image on a web page, you’re pretty much stuck with a Java applet or browser extension. Scalable Vector Graphics, the HTML “canvas” element, Silverlight and Flash 9 are all limited to affine transformations. A common problem is to combine two photographs in a perspective-correct way. The image of the painting needs a perspective projection to match the background image. Alexander Zadorozhny has written a Flash demo illustrating tessellation of an image to approximate a correct perspective projection. While good quality and reasonable performance can be achieved, there is a large impact on the complexity of the application.
Soon there will be a couple of new options for 3-D rendering in a browser. Flash 10 has pretty complete GPU-accelerated rendering functionality. Webkit is also possibly introducing a 3-D perspective transformation property into CSS. Perhaps this will be taken up by the new standard.