@robotamadeus,
I don't know of any, and am not especially trusting of the idea. If you dial a 900 number, you are going to be charged for something, and it will appear on you phone bill. Not a good idea in my opinion, as you owe payment to one party, and another party has the obligation to provide goods or services. There me be such a service as you describe, and it may be legitimate, but I wouldn't mess with it.
You will pay your phone bill, whether you like it or not.