At the Disney Parks, visitors can purchase “Magic Bands”. These bands are programmed with your ticket details and allow you access to designated areas, much like the RFID cards that you’re issued with. Some activate different lights and sounds, depending on which one you’ve bought. These bands are priced between $12.95 to $32 depending on which one you have. It’s a pretty cool, (if expensive) way if interacting with the park.

I’ve tried looking for these on ebay, but for some reason they’re difficult to track down.