How to Improve Meetings When You're Not in Charge

Participate
You can help the meeting when you help others participate. If you see a quiet person trying unsuccessfully to break into the conversation, say "I think Jennifer has something to say" or "Jennifer, were you about to say something?" Don't force her to speak, but make an opening if she wants to take it. You can also help when a speaker is interrupted: "I think we may have cut Josh off before he had a chance to finish. Josh?" Then Josh can finish his thought if he wants to, and the interrupters will be a bit more aware of their behavior.

Rephrase
Sometimes rephrasing can help when someone is stuck on one point: "What I hear you saying is XYZ. Is that right?" Rephrasing helps people feel heard and can break the logjam.

Comment On What You Observe
Sometimes it helps to comment on what you observe: "I think we've covered that already," can help get people moving again.

Deflect Offline Discussions that Take Too Much Time
When a couple of attendees get involved in detailed discussion that others don't need to hear, point out that it can be handled offline after the meeting. "Can you guys finish up that discussion offline?"

Summarize
Summarizing important points and decisions can help the group move forward. "Here's what I heard us agree to. Is that right?" Don't be upset if people disagree with what you've said-you've just turned up the fact that people really don't have a common understanding. Once you've surfaced the misunderstanding, it's more likely to be resolved before everyone leaves the room. (One less thing to blow up later!)

You may not be able to solve every meeting problem when you're not in charge. But you can help many meetings to run more smoothly. After a while, people may start following your cues: they'll write an agenda, pay attention to who they invite, and become more aware of the interaction. And, you'll look good, too.

Reference
The ROTI Method for Gauging Meeting Effectiveness by Esther Derby