Is your Ceremony being held in a place that has special meaning to the bride or groom? Is there a place nearby where you used to play as a child? Take time to sneak off and have special pictures taken. If these special photos are planned in advance they only take a few minutes and give the couple a chance to capture a very special moment.
Point out special people who are attending the wedding to the photographer in advance - Grandparents, special childhood friends, anyone of whom you might want candid photographs.
Don't forget about the rehearsal dinner! Talk to your photographer about package options or assign a one of the rehearsal dinner guests to camera duty.