Are there any reasonable escrow services out there for designers? It seems that a third party with a list of conditions for both sides could hang on to a predetermined amount of money and the digital assets until both parties agree to release.

There are perhaps caveats that I've not considered, but this idea comes to me again and again when I hear this kind of story (again).

Edit: Guess I also have to throw in here that I am continually amazed at the number of people who are afraid to do the dirty work of being in business (drawing up contacts, negotiating, calculating margin, saying NO, etc).