I would love too see a service where it's possible to be listed also as escrow, by using this kind of escrow
http://www.bitescrow.org (it should be implemented direcly on proxycoins in this case)
Chose the price (free/fixed/%), and make it automatically/easier. Invitation A/B will be given to the buyer/seller without any intervention from the user-escrow.
The user-escrow will need to act only for disputes.
Buyers/sellers will have to agree on with user-escrow chose on the list of escrow.
If it is a free escrow-user, after his decision the bitcoin will automatically go to the winner.
If it has a fixed price/%, after the escrow decision the service (proxycoins in this case) will wait for the correct amount of Bitcoin on a dedicated address. The winner will have to sent this bitcoin before receiving his own.
I'm not sure if I've explained correctly, english isn't my primary language