We have all been in attendance at business meetings that got out of control. The yelling, the droning on and on, the pointless discussions about nothing. The list of pet meeting peeves goes on and on. In fact, I know a number of people who actually refuse to attend meetings, sending - you guessed it! - their virtual assistants in via Skype or their on-site administrators in their stead. While you may not be able to control other people's business meetings, at least you can exert some control over your own agendas.
Consider using these techniques to help you keep control of your meetings:
Carefully monitor your body language
Particularly if someone comes into the meeting expressing strong, controversial opinions, you will need to be careful that your body language does not convey an opinion - particularly approval - about the statements that they are making. Hopefully, you will be able to reign that person in by ignoring them or expressing tacit disapproval, but in some cases you may have to deliver some calm, clear criticism using plenty of eye contact.
Paraphrase other's statements
If you are moderating a discussion, then paraphrasing what someone else is saying can help them clarify their intent and help others better understand the concepts that they are expressing. It also can help limit angry overreactions to statements that may have simply been poorly phrased.
When things have gone far enough, call for action.
As the leader, it is your job to help your team complete its mission. This means that ultimately the group needs to leave the meeting with a plan for what comes next. Even if the conclusion is that more discussion is needed, at least you will end on a positive note and a consensus.