This is currently my favorite effects plugin. I have TONS... but this one is soooo cool.
I like it's various modulation routing settings. It's the plugin I know of that is able to do the FM functions it can do on incoming audio signal. Seriousely a sweet plug for experimental.
I've been running my guitar through it for synth like control of pitch and, of course, Amplitude and Ring modulation. The interface is REALLY nice especially for something free! This is truly a gem in the ever expanding list of amazing freebies. Whoever you are that made this... I love you.