So we all agree meetings are one of those necessary evils - some communication does really require face-to-face interaction. But how you as a leader handle meetings are critical to set the environment and make your employees more effective.
First, respect the time of those that you require to be at a meeting. Several shorter meetings with fewer people makes better use of your employees time. If you have a three hour meeting, there will be people there that may only bee needed for the last portion of the meeting, which may actually never happen because you run out of time. Thus, I recommend short meetings -- rarely over an hour. I also recommend meetings 10 minutes less than an even hour to allow your employees get to other meetings they may have with their own employees. And most importantly, stick to the schedule and if the meeting time comes to an end and the decisions that were required don't happen either reschedule the meeting or agree to extend the meeting only long enough to get the objectives met. AND, be sure to allow anybody in the meeting to leave if there is another appointment they need to meet. Ensure if they are critical to the meeting, that the reschedule option is used.
You will find that if you stick to the posted meeting length, more meetings will conclude with decisions in the allotted times. I have seen this in action and it works.
Secondly, I recommend you adopt a "Meeting-Free Monday" or some other day of the week. This will allow your employees/supervisors to plan recurring activities (or just a break to catch up on weekly things that never seem to get done). Be sure your people know that this is the day that meetings are only scheduled in extreme circumstances and are to be kept to the shortest time possible to get the job done. You will find that meeting that you just knew couldn't wait until next week, keeps just fine.
Finally, make sure meeting objectives cannot be met in some other forum such as a broadcast e-mail or sharepoint post. Also, don't be afraid to cancel recurring meetings if there just isn't enough business to justify the expense.
So in summary, shoot for 50 minute meetings, respect the end time, have more shorter meetings vs one wamma, jamma long meeting, invite only those necessary to get the job done, support a meeting free day each week and if possible, avoid a meeting all together.