Ever created a To Do in the Reminders app, but then realized it’d work better as a Calendar event?
Just drag and drop it from the Reminders app onto the Calendar app window. However, this must be done a special way — click and drag at the right of the entry in the Reminders list (just to the left of where the ‘i’ icon appears). If you click and drag anywhere else, OS X will assume you want to edit the text of the To Do.
This doesn’t work the other way around, however — dragging an event from the Calendar app onto the Reminders window won’t turn it into a To Do. If you drag the event onto the Reminders Dock icon then you’ll be prompted which list you want to add it to, but it won’t actually be added. This is obviously a bug. For what it’s worth, you can’t drag a Reminders entry to the Calendar Dock icon because it’ll refuse to accept it as a drop target — another bug!