Agner Fog's ForwardCom

ForwardCom is a project for development of a new open instruction set architecture and the corresponding software standards. The intention is to investigate what an ideal computer architecture may look like and to design a complete computer system that is more efficient than the currently prevailing systems, such as x86, ARM, etc. Starting from scratch and making a complete vertical redesign allows us to learn from the history of past mistakes and get rid of the heritage of old quirks that hamper contemporary systems.

http://www.forwardcom.info

Handmade at heart!
Now on Github : https://github.com/ForwardCom
I have been following Agner's work on this. I am interested in his approach to variable length SIMD.