fukuhara: Translation Party is a quite amusing application. It translates english phrases into japanese and then back to english. It continues translating between those two languages until it gets same english phrase two times in a row. Phrase in this link is from the description of this board. Experiment with different phrases and you might get some amazing results.

I have very limited knowledge of japanese but i still find this site very good fun. It should be even better if you're fluent in both languages. It really shows how automated translation still has a long way to go.