The quality and effectiveness of meetings varies greatly. For my environment, calls where we're brainstorming a problem or hashing out some details of how $the_thing should be approached tend to be the most effective. These meetings tend to be rare and usually result from trying to work on a problem over chat where it's determined voice and visual aids are going to be more effective for communication.
In my experience, majority of meetings are unfocused, which leads to everyone's time being wasted, or are meetings for announcements only without any need (or intention) for real-time collaboration -- the meeting that could've been an E-mail.
