This cleverly named application continuously transcribes speech to text in real time using the web speech API. It currently only supports Chrome, as support for the web speech API isn't very widespread in other browsers.
Speech to Text Transcriber is designed as an inexpensive solution for assisting the hearing-impaired in situations where lip reading just doesn't cut it, and where hiring a professional to create live closed captions or translate to ASL would be cost-prohibative.