Scenario:

Joe wants to meet Jack, Paul and John and knows he is available at time T1 on date D1 or time T2 on date D2. Also, the meeting could take place at place P1 or P2. Before setting up a formal meeting, he could send a poll to those persons and they would respond with what suits them best.
Once the initiator has all the info he needs, one or more events could be suggested to Joe that would accomodate the most people at the same time, and maybe suggest secondary events for other people to catch up...

In the web interface, the double-click of a suggested event would automatically open an even creation window with the parameters pre-entered.
The format used for storing those polls could probably be based on the "VAVAILABILITY" spec (http://tools.ietf.org/id/draft-daboo-calendar-availability-01.txt) or a derivation thereof.