I think it depends quite a bit on what your end goal is. If your end goal is to make a desktop application that have a visualization component that runs on the

I think it depends quite a bit on what your end goal is. If your end goal is to make a desktop application that have a visualization component that runs on the mac, then using objective-c, cocoa and the graphics frameworks in OSX will be great. If you want the application to be on the web, have a look at Flex for the visualization stuff. It uses Flash to render everything so it works pretty well across platforms.