Who doesn't love a meeting?  They fill your diary, make you look important, give the illusion that something is happening and allow you to let others know just what you're thinking (assuming the other attendees are actually listening and not just thinking about what they want to say).

if you find yourself regularly attending meetings where there's no clear purpose and no solid outcome then it's very likely you are wasting your time.  When meetings are used as a substitute for decision making and positive action then your company is most likely on a slow slide to obscurity.  

Whether it's a regular meeting or an ad hoc gathering, always ask what you're trying to achieve.  Agree a purpose and an outcome.  Appoint a leader, keep to time and use an agenda as a framework (but you don't always have to be too strict on this, stay flexible and adaptive) .  And don't let the meeting turn into a series of showboating from a few individuals.  Each person should contribute, otherwise you have to question why they are attending.

There has been a lot of research indicating that more than 8 people in a meeting becomes counter productive, so keep it small.

And just because you've booked it for an hour doesn't mean it has to take an hour.  If you can all agree the outcome in 10 minutes then you're allowed to close the meeting. That may come as a revelation.  If there's a clear purpose that will be obvious and nobody should feel aggrieved that they are not getting their money's worth.