Instaprint machineRemember Polaroid prints? Give attendees a trip down memory lane by installing Instaprint machines around the venue. Participants take pictures with their mobile devices via the free app, process them in the printer, and the retro-look Instagram photos come out on paper (which can be customized with logos) imprinted with your event's hashtag. Photos also are saved in an online gallery on photo-sharing site Instagram for later access. Rental cost: $5,000 in the New York City area (additional costs apply in other cities).