There's actually a whole class of keyboards like this [1], the most popular being the Jankó keyboard [2]. Here's [3] a cool demo by a Jankó virtuoso.

[1] http://en.wikipedia.org/wiki/Jank%C3%B3_keyboard

[2] http://en.wikipedia.org/wiki/Isomorphic_keyboard

[3] https://www.youtube.com/watch?v=cK4REjqGc9w