Knitty is a research prototype for computer aided crochet and hand knitting design.
It was developed by Yuki Igarashi and can be downloaded as freeware. The Knitty demo is a java application, which only runs on Windows, since it relies on ActiveX for 3d graphics.
In the pattern design window, 2d diagrams are displayed visually as amigurumi pattern disks, which are used frequently inside japanese craft books.
Knitty is a proof of concept and very buggy.