A friend of mine told me one technique his boss used for keeping group meetings on time. The last item on every meeting agenda was called Rumors and gossip.
A group meeting is sort of like a mandatory watercooler session. Everybody is now in a room sitting around a table, and you naturally start discussing whatever rumors you've heard about what's going on in upper management, that newspaper article about what your competition is up to, or whether you think your supplier is really going to deliver that component on time.
Whenever the meeting started to drift into rumors and gossip, the boss would simply say, "Save it for rumors and gossip." And then the meeting would reach the Rumors and gossip stage, and everybody (including the boss) could gossip about whatever it was that they heard from a friend of a friend. The boss might confirm some rumors, deny others, say "I don't know either," or even "I don't know, but I'll try to find out." This was also a good time for the employees to raise their concerns about the project.
From what I could gather, Rumors and gossip was a big hit. Everybody knew to save their rumors and gossip for the end of the meeting, allowing the rest of the meeting to stay on track, and it became the part of the meeting everybody looked forward to.