What role should a DM fill at the gaming table?
Sure, he is sometimes referred to as a Referee, but that rarely defines the role in total.
Facilitator, director, storyteller - they are all aspects of the persona of most DMs.
If you were to read and attempt to run many of the recent LotFP releases, especially James's, you would suspect the role to be played is that of adversary - or even destroyer of parties (Monolith From Before Time and Space comes to mind).
I think, above all, the DM is there to ensure that the group has an enjoyable time, and the role adjusts to the party's needs.
How do you see the DM's role?