Voice to Text - Free! Jott™

Jott™ - Official Site

Ok, this is really cool. You dial a toll-free number, and speak your message. The service (free, for now) transcribes what you say and forwards your message to basically anywhere you want (e-mail, or some other service...like Twitter).

If you speak clearly it works perfectly (you can even spell things). I tried to break it by slurring the word "disestablishmentarianism" - I couldn't. I'm sure it uses a spell checker.

The only limitation I've noticed is that each "jott" is limited to 30 seconds. That seems like a long time, but if you are speaking slowly and clearly it's about 75 characters (literally, a jott).