We get lots of people complaining in deal threads and voting cold because of past experiences with retailers. These people could use a forum to talk about these issues, giving them a reason not to turn deal threads into retailer hate threads.
It would also be good for people to easily be able to view the recommendations of the HUKD community with regards to the best stores. This would ease the worries of people new to buying online/who haven't ordered from the store in question previously.
This would be very simple to do - Create a forum, make a rule about only having one discussion thread for each retailer. No effort required to make and the threads for each retailer would be easy to find with only one allowed for each.