There's Rosetta Code to compare short programs in different languages. Not as handy as what you are asking for, still it is educational
To try it out I started at http://rosettacode.org/wiki/Category:Perl_6 to find all the pages that have P6 examples. I chose "String Case" and then clicked on Perl, which got me to the P5 example, and right after it was the Perl 6 since each page is alphabetical by language! (That site is screaming to be fed into a machine-learning-code-translator!)
