NPR had a short clip last week on a girl that can speak backwards. Well, not really. She's just turning the letters in the word around pronouncing it as something that would be spelled similarly. Listen to the clip for a more full explanation.
This did spawn a thread in the conlang mailing list about jokelangs or ciphers that employed "backwards English". Gary of fiziwig.com came up with Ersever to make backwards English more easily pronounceable. It's fun in the same way Pig-Latin is. Definitely worth a read.