mucoder has released another freeware called tonespace 2.0. its an chord-generator running as vst plugin.

what is tonespace?
* it’s a different, more intuitive music keyboard, combined with a chorder
* It supports over 50 different grids, 14 scales, 18 keys, 30+ chord types and 10 chord voicings
* it can function as a VST or Audio Unit plugin, processing incoming MIDI events and/or generating outgoing MIDI
* you don’t need to use MIDI though: there is also a standalone executable which contains its own little synth for a fast start

what can you do with it?
* you can play and visualize chords while you move the mouse around in a grid-like space
* you can learn how musical scales and keys work, and how chords relate to these, using the simple octave-based spaces
* you can visually discover how chords map onto surprisingly simple geometric shapes in the more advanced spaces
* you can use the chord-generation algorithm to generate chords from these simple shapes in the advanced spaces

download-link: http://www.mucoder.net/en/tonespace/