For what it's worth, I used to do transcription for an oral history department at a university. They would tape interviews with people who had memories of things-back-in-the-day, and we would transcribe them into a script format according to their internal standards. It was nice, because the tape players we relied on were foot-operated, so you could go over the mumbled/garbled/tricky parts over and over and over as many times as you needed to without taking your hands off the keyboard.
So-- that was in the mid-90's, and isn't useful for employer recommendations, but I wanted to point out one aspect of transcription that can be frustrating, and if you plan to get into transcription, figure out how you plan on dealing with it. I would presume that a place that takes transcription seriously would have some kind of tools available--- although obviously, a freelance-work-from-home setup would have different resources available than a central office location.
Good luck! Let us know how Rev.com works out.