Heartburn is a Windows VSTi with 3 oscillators (Including a waveform called Bastard!), a filter and various modulation routings, but it's also got some cool features, including an (optional!) auto-mutator which twiddles patch parameters every time you play a note and loads of formant controls.

The author is looking for feedback on what features would make you want to buy it, and how much you feel it would be worth should it get a spangly interface as opposed to the default host supplied interface it has now.

So let him know!

They have a bevy of VST effects there too...