The following 3 line implementation of RSA in perl is pretty cool:
#!/bin/perl -sp0777i<X+d*lMLa^*lN%0]dsXx++lMlN/dsM0<j]dsj
$/=unpack('H*',$_);$_=`echo 16dio\U$k"SK$/SM$n\EsN0p[lN*1
lK[d2%Sa2/d0$^Ixp"|dc`;s/\W//g;$_=pack('H*',/((..)*)$/)
You can get a up-til-now comprehensive overview of the perl hacker community’s work on decreasing the size of this implementation at http://www.cypherspace.org/rsa/story.html.
Rest in peace Peter Junger!