prototyper's toolbox

        Nothing special here, just a bunch of tools I've been using recently to do rapid prototyping.  It's such an alien concept to me to just throw a bunch of hardware and software into a blender and see what comes out, but it's pretty freakin fun.


Unity
Probably needs no explanation, really good platform for prototyping as it's open enough to do things that aren't necessarily games.


openFrameworks
Everything you need to create rich interactive applications under one roof. This is the model for what easy-to-use SDKs should be.


Processing
It's like an IDE for doing cool graphical stuffs. For you Pythonistas, check out pyprocessing as well.


vvvv
Just found out about this the other day, node based madness.


OpenNI
Definitive framework for natural interaction (gestures, etc). A bit of a learning curve, but good to know.
        So what are some of your favorite rapid prototyping tools?  And if you say UDK, i swear i WILL hunt you down and punch you in the heart...