??ʇuoɟ sıɥʇ ɥʇıʍ ƃuıʎɐןd ǝɯıʇ ǝɹoɯ uǝʌǝ ǝʇsɐʍ puɐ ןɯʇɥ˙sɹǝʇʇǝןuʍopǝpısdn/ʎɐןd/ɯoɔ˙sǝɹıʍuǝʌǝs˙ʍʍʍ//:dʇʇɥ oʇ oƃ

?—ʞɹoʍ ʇɐ pǝɹoq
You type whatever you want to write in the top box and it'll appear upside down in the bottom. Works kind of like Babelfish translating. You can then copy and paste the upside down text into an email, onto a blog or even a ǝʇıs ǝıqǝǝɹɟ!

http://www.sevenwires.com/play/UpsideDownLetters.html