Rollers are a common fat bike grooming implement and Wildcat seem to be making some of the best right now: http://www.wildcatgroomers.com/home.html
Compaction drags are another option for grooming. This is a compaction drag used in Traverse City Michigan. The crew up in Marquette, MI are always ahead of the curve on grooming and have a lot of pictures of their drag(s) listed on their Facebook Site. Yellowstone Track Systems is making a fat bike drag that looks really interesting.
V-plows are another interesting implement. The Northern Michigan Mountain Bike Association has a good picture of their V-plow (as well as their drag) listed on their site.
I never got back to discussing during the podcast the role a plow can play in grooming. In heavy snow areas using a plow on the front of the towing vehicle is a super-versatile tool. If designed correctly it can “roll” new snow and preprocess it helping to transform powder into good compacting snow without moving it off the trail. A plow can also help to maintain or correct the camber of a trail. In downhill grooming circles the plow can be used to move snow to make features and I could see that being a very interesting direction for fat biking grooming to go!
Not discussed in the show but I would love to see someone experiment with a power tiller because it would potentially take some of the load off the pulling vehicle. The gold standard in ski grooming is the use of a Pistenbully which uses a combination of the plow on the front to correct camber (and other things) and preprocess large quantities of snow and a power tiller in the back to process the snow. Obviously, a very different beast than what you would use for fat-bike grooming but the concept of powering the processing of the snow is something that could be applicable to fat bike grooming. This is a discussion about ski grooming and the use of a self contained powertiller that would be pulled by a seld or other vehicle and may work for fat bike grooming too: http://s8.zetaboards.com/snowgroomingtalk/topic/8181840/1/ Looks like the crew up in Marquette are already experimenting with this type of impliment!