We've been working on this recently- it's not yet a public release, but it is useful (and free). Just make an account and upload the MP3. Allows you to read, listen or both at the same time. Takes about 1/2 the time of the audio file to process.
See my adjacent comment. Also, to add some more info here; the site will soon allow you to share the transcripts, so we don't all have to upload a copy for ourselves. We're also building editing / revision tools.
