My friend and former boss, Paul, from The Princeton Review has a great habit. Whenever someone shares an idea or opinion, he asks a follow up question or two to make sure he understands it. Then he restates it in his own words just to make sure he's got it right. It doesn't matter if he totally disagrees with your statement the first time he hears it. He'll first make sure he understands it completely before he offers his opinion or retort.
The upshot of this is that while everyone else in a meeting is busy thinking of what they want to say, Paul is busy understanding what's already been said. He's always the first person to get it. It makes him seem even smarter than he is (which is already very smart). What he eventually says in return is always insightful. And everybody listens to him as a result of it.
It's not difficult, but most people don't do it. I'm going to try to do it myself a lot more often.