The new escort quest for the jubilee event is an excellent way of grinding both renown and the protector's bounty boxes. You only need one person to have the scroll with the quest to get him moving (which is a fairly common drop), everyone else can then tag along without having it and still get the rewards. After every combat the merchant and his horses will drop either a box or some renown for everyone present... which adds up to quite a number as he gets ambushed several times, walks through a bunch of existing mob groups and you can even pull some more on top of him to make him drop extras.
There are a couple of these merchants in different zones - I escorted one in Blacklake District today and there was a huge crowd following the merchant's every step, with the low-level mobs getting one-shotted before they'd even fully spawned. With my guildies I've mostly been farming the stronghold version though - it might have been luck of the draw, but that one seemed to drop a much higher number of bounty boxes for me.
It was probably the most bizarre kind of social content I've participated in so far, constantly running up and down the road as a group to escort more merchants. It was pretty fun and relaxing though.
Foreign merchants showering us with gifts... I think Cryptic is sending a clear pro-immigration message here!