User jquinn would like to step in as an escrow agent for Mastercoin trades – thanks for helping out!
To overcome initial trust concerns we agreed on a 5 BTC security deposit to be made to an address of mine. Should jquinn try to scam anyone there will be at least 5 Bitcoins to compensate the victim. Once we have a working decentralized exchange, escrow agents won't be needed anymore and I will send back the 5 BTC to jquinn.
In any case, I won't touch the coins without talking back to the community here first.

Pouncer suggested this method a while ago and I think it's a great way to build up initial trust.

jquinn, here's your deposit address:
1AqgydyfA7F9QT3RisVJi8NdU2NCZeBGGN

People will be able to see the balance here:
https://blockchain.info/address/1AqgydyfA7F9QT3RisVJi8NdU2NCZeBGGN