There are a few personal phone message systems online that will allow you to send a message from text to phone for free, but in a pretty interesting way. However, keep in mind that the personal phone message works only in the USA, so you’ll need a US phone number for this to work.

Britney Spears allows you to send a free personal phone message, with a promotion for her midnight fantasy fragrance. (link)

Mario from Nintendo has a free personal wishlist you can send as a funny voice message to people as well. (link)

Dick Vitale lets you send a free personal phone message in a Digiorno Pizza promotion. (link)