Simulscribe is a cellular service that monitors and transcribes your voicemail. When you receive a message, it converts it to text and emails the message transcription to you. It also includes an audio file of the original message so you can check for errors.
While I’m on the subject of transcription, does anyone know of a program that can accurately transcribe .wav or .mp3? I’ve been looking for a way to convert lecture recordings to text, but have been so far unsuccessful.