I follow a meeting rule which is borrowed from Steve Jobs rule book. I read this in the Walter Isacson biography.
I will attend a meeting if, by attending the meeting, one of two things happen — I gain something from the meeting, or the other folks in the meeting gain something from me.
I follow the same rule when calling for a meeting, and inviting folks to it.
As a corollary rule, I will always _NOT_ carry a laptop to a meeting, unless I am presenting, or if I have been explicitly asked to take notes. The reason is that, if I do take the laptop, I will be distracted and be tempted to work in parallel. This would break the first rule. I will neither contribute fully to the meeting, nor will I gain something in its entirety.
Following these two rules sometimes gets me very antsy when a meeting is poorly conducted. But that is beyond my realm of control. I try my very best to ensure that my meetings are efficient.