I'm bored

Expert /prog/rammers,

The weekend just began and I've got nothing to do. What should I code, and in which language?

Here's the languages I know:
C,
C++,
Common Lisp,
Perl,
Ruby,
and then some Python, Haskell, Java, and x86 Assembly.

Read SICP (seriously) and learn Scheme. Then code some Factorial and Fib Programs ;-)