Inspired by a post in the Beautiful Code blog, Simon Wistow created Acme::Numbers, which lets you do cleverness like this:

use Acme::Numbers;
print two.hundred."n";               # prints 200
print forty.two."n";                 # prints 42
print"n";      # prints 0.05
print four.pounds.fifty.five."n";    # prints "4.55"
print four.pounds.fifty.pence."n";   # prints "4.50"
print four.dollars.fifty.cents."n";  # prints "4.55"

You probably wouldn't want to do this in production code, but like the best of Damian Conway's not-useful-but-thought-provoking modules, it may spark some ideas that you can apply to more useful situations. If nothing else, the source is a fine lesson in overloading and method importing.