ofxGenerative by Reza Ali
While this addon seems very much like a work in progress, it includes a ton of physics-based tools for making generative works. I haven’t done any work in this area, so this seems like a really good starting point for me to begin looking at some code that goes into generative artworks and start to play around.

ofxRP2A03 by Shintaro Matsushima
It’s an emulator of the classic synthesizer from the Ricoh 2A03 microprocessor featured in the Nintendo Entertainment System.  Needless to say, this microprocessor is responsible for creating some of the most iconic 8-bit sounds ever heard.  What’s not to like? You can play with an online version here.

ofxFft by Kyle McDonald
The FFT, or fast Fourier transform, one of the most essential tools for signal processing.  Its purpose is to extract frequency information from signals.  It’s just plain useful.  This addon for openFrameworks makes it even easier to use a Fourier transform on streams of audio input to the oF application.  I plan to use it in my ofxAddon assignment to determine the fundamental frequency of voice input.