Starting with the understatement of 2007, "Professional typedesign is complex enough as it is", the extremely clever guys at Letterror have released Superpolator 2, a true MacOS X app developed from their Python library. It's Multiple Masters on steroids! From the website, "FontLab's interpolation tools are based on Adobe's Multiple Master technology. A breakthrough in 1993, but restricting and limiting today. Superpolator remedies that by introducing a flexible way to build interpolation systems. The tool has to accomodate the typeface, not the other way round."