Well, its a group of land owners with to much time on their hands.

Far From it! 

 Landowner groups vary one to another. Let me try to break it down from what I have learned so far in GOM =(Go Marcellus Shale)

1. TRUE LANDOWNER GROUPS Some groups have formed consisting of Land owners in desire to run the show for the benefit of all its members. They are probably the best as because they are Land Owners.  The lease terminology for protection of a landowners property is of a high priority to them and I would say probably the best in trying to get the best lease possible both in terms and money. The higher the membership and acreage the better bargaining power they have with the real players in drilling and producing.  Usually the Landowners establish a fee to cover legal fees involved with Lease preparation, perhaps meeting cost and communication with its members. You can usually remove yourself from the group without peanlty (unless the group is at the time actively marketing the group acreage as a whole) These groups you could label as non profit

2. Legal Land Owner Groups I used this term as I find it more accurate than calling it a Land Owners Group. These are usually created by a LAW FIRM that is in the business to make money for themselves. They assemble Land Owners and try to get the landowner to try and join their venture.  Fees are charged to join this group, restrictions upon dropping out of the group are also imposed to some extent.  Some charge a % of the bonus money they can negotiate the land for upon your acreage involved , some even take a permanent % of your royalty (forever). Some are looking at just a straight $ fee per acre after a lease has been marketed and sold. I myself question this practice as what might be in the interest to them might not be in the interest of the land owner.

3. FALSE FLAG LAND OWNER GROUPS These types of groups are the snake oil salesmen. Usually they appear as land owners and give a pretty good story. The catch to this is usually the creators are only interested in getting you to sign with them were they can reassign your lease to another party for a profit form themselves. (Lease Flippers) 

4. You Well you can do it all by yourself if you want to, depending upon the acerage you own and what has been leased around you will make a impact upon what you may receive in terms of lease bonus and royalty % . You should by all means utilize an attorney in doing so.

 There you go a brief explanation, research do your home work and buy all means good luck.