Idea: in Mac OS X, there exists an API called Core Image, which is used for fast 2D graphics filters. It can do things like bloom, blur, and distort an image all in real time. Why not take advantage of this in Blender? It could be a faster method for applying image effects in the compositor, or be used for faster procedural textures.
I tried writing a plugin for this myself, but failed. It looks like it may need integration with Blender itself. Maybe this could be a feature of Cocoa-Blender.