One interesting aspect of this is just whom they consider to be Inklings -- Tolkien and Lewis, of course, as the co-founders and by far most famous members, with Williams and Cecil in the second tier (a lot of Inklings scholars forget how distinguished a scholar Lord David was*). Warnie and some books about the Inklings round out the list -- rather surprisingly there's no Wain here; perhaps they felt his work went too far afield and shd be grouped with the Angry Young Men instead.
Most interestingly of all, they include Roger Lancelyn Green among the Inklings' members, giving him equal billing with Wms and Cecil. I know Doug Anderson has argued that a good case can be made for RLG as an Inkling but I think this may be the first time I've seen it taken as a given. Interesting!
And, in a related note, ABEbooks.com likes to send out monthly announcements of which ten books sold on their site for the most during the previous month. Tolkien ranked on top a few months back; this month, he's #7 behind Fleurs du Mal and Dr. No and Edward Gorey, ahead of JFK and Huxley, with a set of the first-edition LotR:
current book: PICTURING TOLKIEN
current e-book: book five in the 'Royal Spyness' series by Rhys Bowen
current audiobook: THE FURTHER ADVENTURES OF SHERLOCK HOLMES  and
THE GIRL WITH THE DRAGON TATTOO (just started)
*there's a reason he got an Oxford professorship so early. Though he didn't deserve F. R. Leavis's elevation of him into the epitome of all that Leavis thought was wrong with English literature and academia (i.e., that too many people listened to Cecil rather than Leavis).