@ninjacharlie:
First of all: there are some nice small or minimal lisp interpreters
out there. I can for example think of femtolisp
(https://github.com/JeffBezanson/femtolisp) or tinyscheme (https://github.com/armornick/TinyScheme).
So I don't think there is more need of minimal lisp interpreters.
Still looks like something fun to do.
Just wanted to tell you.

I have released the 0.1 version of fred (www.github.com/scharlatan/fred).
It is still a bit buggy sometimes, but mostly works.
Maybe you want to try it.