Soundminer
Setting up Reaper to grab MIDI and send it over ReWire to Soundminer took me a few steps so I captured a video to demo it. Make sure your MIDI device is connected and powered on before launching Reaper, and with all ReWire devices, launch Reaper first, instantiate the plugin THEN launch Soundminer.
Very simple example, but you can map as many controllers you have to any plugins. You can drag and drop the plugins to re-arrange and the mappings will follow. So if you always have CC#26 going to Ring Modulator Depth you could be messing with pitch, scrubbing through the sound and controlling that parameter(and others) at the same time. All the while recording your masterpiece to a file to snip the interesting parts out of later!
Download my Reaper project here