Rails

This one has to be seen to be believed. Fortunately, this is easy, assuming you can play QuickTime movies (and have a high-resolution screen; 1024x768 wasn't enough to see all the action).

Rails is a web application framework written in Ruby. The thing that's different about it is

Rails shuns configuration files and annotations in favor of reflection and run-time extensions. This means the end of XML files telling a story that has already been told in code. It means no compilation phase: Make a change, see it work.

I develop web applications in Java for a living, and the extent of how much was accomplished during that 10-minute video floored me. I suspect that the day job will remain Java for the forseeable future, but the stuff I do for the fun of it is about to get a whole lot more fun.

Thanks to Dion Almaer for the link.