I got this idea from Psychotic's Marketplace Bans website idea.

Basically, the idea would be something like this:

User A wants to buy User B services (Amazon Refunds?), but User B hasn't any vouches yet and User A wants the service so hardly, so they agreed that the refund service costs $50, so User A would go to a page (or it can be a mpgh subdomain w/e) to send Bitcoins (because they are irreversible!, Paypal Donations are too? dunno) to a MPGH Wallet, and User A has to fill a form like this:

User B MPGH's Name:
Money:

and once he sent the money, basically the server gives him two keys, one Public Key and one Private Key.

User B on the other hand, can basically see the 'transaction' using the public key (to see who's the buyer, how much money and the MPGH Username's intended to send), once he sees that User A sent $50 he can basically provide the Service, and then the buyer sends him the Private Key so User B can withdraw the money. The Private Key and User B MPGH's Name have to match with the person who wants to withdraw that money.

So, there are 3 possible situations:

- The buyer and the seller uses the service as intended.
- The buyer doesn't want to give the seller the Private Key. (a MM can be used - fixed)
- The buyer doesn't have Bitcoins to trade. (I'm not sure if Paypal Donations can be reversible/chargebacked, so that could be an option too! Anyways, the buyer could exchange it)

From my PHP knowledge, this can be done implementing a Bitcoin API. And MM's would only have to worry about some problems because all this service would be semi-automated.

@Psychotic
@arunforce
@Flengo