MeetMe.At allows you to propose up to 4 dates and 2 locations for your meetings. The invite is broadcast to your friends who simply vote on the dates they can make it and what location is preferable. The app even notifies them of pre-existing meeting clashes in their calendar.
As your friends vote, you can see instantly which dates work best and simply lock in a finalised time and place. Easy.
Features GPS maps integration, chat feature and publishes to your phone calendar. Requires Android 2.3.3 OS or higher.