Programs for a Sorcerer Supreme

Hello, /prog/.

I know the subject is vague, so let me explain:

I'm confident I know some programming languages very well, but I feel my knowledge is lacking when it comes to many others. So I'm looking for programs that can sharpen up my skills. Stuff that requires one to use most of a language's features. What would you suggest?

C - compilers. Device drivers?
C++ - game engines?
Scheme - an interpreter?
Common Lisp - ?
Haskell - ?
Java - ?
.NET - ?
Scala - ?
Python - ?
Ruby - ?

>>31
I agree, Common Lisp is not a pure functional language, neither is Scheme, ML or OCAML. But Haskell and Erlang are. Lisp was not originally intended to be a programming language but was a mathematical study of computation by John McCarthy and was implemented as an interpreter by Steve Russell one of his students. So Lisp was always open to different ideas as it was never intended to be a specific language design.

>>32
Yes, OP did not ask for languages to be grouped, but he should have, because its wasteful to start out learning a bunch of languages that are similar to each other unless you happen to be specializing in a specific type of programming. If you want to get good at something like programming you have to make a choice on one or two languages to start out and then focus your energy on that language.