A new version of one of the best tools for rapid game development has just been released. It was pretty damn good already and it has gotten an a lot better.
Check out the new features here:
You should also check out their live demos:
http://unity3d.com/gallery/live-demos/tropical-paradise
To view the demos you need to install the webplayer which is a 1-click install that works even without restarting your browser!