Albert and Bob are both interesting to find the counterparty about a specific product X.

Beside use google search or they both know each other's contact already, they can leave message in BtcDealMessage by the BTC Deal Message Input Form to inform the interest in bitcoin community and get notified by the RSS feed mechanism.

For example, Albert may first input a message in the form:

From
  Albert's bitcoin address
To
  all people
Message
  Does anyone want to buy X ?  of course, I mean in BTC

And both Albert and Bob subscribe to two RSS feeds about this. One feed is message about "to me", the other is message about X. So Bob will get notified and know Albert's address and Bob can input a message in the form:

From
  Bob's bitcoin address
To
  Albert's bitcoin address
Message
  I want to buy X.  How many stocks you have?
  Do you mind we chat on skype or else?
  btw, kindly show me that you control that address by adding the signature on a message

In this way, they can subscribe to even specific RSS feed about message "from the other" "to me" to start more specific communication:

From
  1ESHzedmNkAF9Cjv11uFqmCkLCj3B8DMeA
To
  Bob's bitcoin address
Message
  I have 300 kg X
Signature
  ICaSTbmPW7iIguf2XzH4ocuHHRzCPnkpHEserEegwL9cdocbvjaxAtdlTCQn74YdEJ7/6t/Gw7xRGQ6WP8KviDE=

And continue by the RSS mechanism or by skype if they ok