how about things like this?

#!/usr/bin/perl
use strict;
use warnings;
my@mname=('Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec');
for(grep/\/\d+\.(?:gif|jpg|png)$/,map{glob"$_/*"}@ARGV){
  (my$newname=$_)=~s/(\d+)...(....)$/${\((gmtime$1)[5]+1900)}${\($mname[(gmtime$1)[4]])}${\((gmtime$1)[3])}-${\(join'.',map{0 x($_<10).$_}reverse map{(gmtime$1)[$_]}0..2)}$2/;
  rename$_,$newname;
}

I wrote a program in letterless C once. No letters or digits allowed in the program, except for one #define to give a way to access an input function and an output function, and the prototype of main.

That is called obfuscated code. See http://www.ioccc.org/ (International Obfuscated C Code Contest) for some great C examples, such as a flight simulator with airplane-shaped source code.