I'm half-heartedly looking for apartments on craigslist (I don't know where I'll be working next, so that limits things, somewhat), and have several times run across this one: Some one advertises a beautiful apartment for a ridiculously low price. When you ask about it they claim to have been transferred out of the country, and have the only set of keys with them. But, they're willing to use TNT as an escrow service: they'll deposit the keys and contract with TNT, and I wire TNT the first month's rent, or a deposit, or $$, in any case. Once TNT has received and verified both the keys and the money, they'll send me the keys, and the apartment owner the money.
Except that I've spoken with TNT in person - they're a shipping company, similar to FedEx, that operates in Europe and other places. They offer no escrow services.