Given how long it takes to resume productive work after a meeting (for people on the maker's schedule [0]), the productivity value of getting meetings right can be pretty big.
What do you do to reduce the number or cost of meetings? (either as an individual or as an organization)
The main technique I have been using lately is preemptively blocking off chunks of time long enough to get something done (3-4 hours), and declining any meetings that are later scheduled over that time. This groups meetings together, incurring the "resume cost" once per group instead of once per meeting.
[0] http://www.paulgraham.com/makersschedule.html