Hello 
Maybe some of you guys will be interested.
I wrote a small Lisp interpretter embedded in Ruby.
The emdedding is very tight - Lisp macros are Ruby Proc objects
and Lisp lists are Ruby Arrays (so actually cdr/cons copy).
It is somewhat more Scheme-ish (or even Goo-ish) than Common Lisp-ish,
but the macro system is more like Common Lisp's.
[obj method args] is a reader macro for (send obj 'method args),
which expands to obj.send(:method, *args).
Here are some examples:
; Fib function
(defun fib (n)
(if (<= n 1)
1
(+ (fib (- n 1)) (fib (- n 2)))
)
)
(print (map fib '(1 2 3 4 5)))
; A small HTTP server
(ruby-eval "require 'webrick'") ; import module
(let HTTPServer (ruby-eval "WEBrick::HTTPServer")) ; bind class name
; Configure the server
(let config [Hash new])
[config set 'Port 1337]
; Tell the class to make us a server object
(let server (send HTTPServer 'new config))
; Tell server to call our Hello World handler
(send server 'mount_proc "/hello"
(lambda (req res)
[res body= "<html><body><h3>Hello, world!</h3></body></html>"]
[res field_set "Content-Type" "text/html"]
)
)
; Tell the server to go !
(send server 'start)
Because it supports macros you can do things like:
(def-server-html-mount server "/hello"
(html (body (h3 "Macros greet you")))
)
and that's pretty cool, because Ruby itself doesn't support macros
and now you can use macros almost in Ruby 
The download: http://zabor.org/taw/rlisp/
Documentation is only on my blog for now:
* http://t-a-w.blogspot.com/2006/07/rlisp-lisp-naturally-embedded-in-ruby.html
* http://t-a-w.blogspot.com/2006/07/rlisp-gets-basic-oo-support.html
* http://t-a-w.blogspot.com/2006/07/rlisp-gets-http-support.html
It uses Martin Traverso's Ruby port of ANTLR 3 for parsing.
Well, that's pretty much all
If you have any questions about it, just ask
(on the mailing list, by private mail, or on the blog)