Another gem post of Top 10 tips by Guy Kawasaki covers How to Be a Great Moderator.
He covers preparing yourself, not over-preparing your panelists, making them look smart, and keeping things moving.
My favorite tip discusses not letting panelists spew "bullshitake." I particularly got a kick out of Guy's Standing Up for the Audience tip in which he says:
A good moderator is the audience's advocate for truth, insight, and brevity--any two will do. When a panelist makes a sales pitch or tells lies, you are morally obligated to smack him around in front of the audience.
For a nice complement to his post on moderating, see Guy's earlier post for participants on a panel at: How to Kick Butt on a Panel.