Interesting site this – The Rational Keyboard. Has to be seen and played with – best explained by the man himself: “The Rational Keyboard is an HTML5 web app demonstrating a consonance model injust intonation. It’s kind of like a piano with infinitely many keys (one for each rational number) that move around and resize based on what sounds good.”
Essentially – play around with it, fascinating work and utterly mesmerising – looks great too. You can spend a long time here playing around with the sounds and watching how the keys blend and change size.