This reminds me of an idea I had for a product: place value on your and your colleagues time by creating a market for it. The market runs in the calendaring application - you are allocated a certain amount of everyone's time to take for meetings. If you want or need more than your allocation, you have to trade for it. That way you are forced to invite only the people you really need, it quickly becomes obvious whose time is most important, the overall amount of time spent in meetings is limited, and people become cognizant of the "value" of others' time. It could be built as an outlook plugin, even.