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 - ?

>>10
Unix? Fuck you, I use DOS. Real men implement their own security. My security is a gun that shoots people who try to use my main machine, man. It's simple and effective.

I have an enormous brain and an even bigger penis. While I work out, I dictate my programs in a Brooklyn accent to a secretary in a skanky maid costume (she knows she likes it). I know all the MIPS, SPARC, and x86 opcodes by heart, and I use compile time constants for control flow. In the middle of winter I run naked through the Himalayas and drink a gallon of gatorade so I can write C programs in the snow.

I can bench press all of Microsoft.