Just paged thru @ofxaddons and found some fun looking addons. You should follow this twitter if you’re into openframeworks!!
ofxMacMouse lets you control the mouse through your oF app. This is usually annoying to get to work but now it probably isn’t.
ofxChromaKeyShader does the greenscreen thing for you.
(and here’s a shameless plug for ofxLeapGestures — you can train it with machine learning to recognize your own hand gestures from a leap motion controller!!)