Image by schoschie
It’s lineto.com, a swiss font foundry and design bureau.
For navigation, they use a floating palette imitating the OS X Finder’s column view . Also, there’s the TypeWriter, a tool to test out their fonts, and it’s controlled by another floating palette that feels completely like – and is just as powerful and functional as – the text/type palettes from some of the professional design applications.
But the best thing is: IT IS NOT FLASH.
If I recall correctly, this interface has been online since around 2002 (coinciding with the date on the JS library). It was extremely impressive back then, but it’s still hot today.