Wet festivals suck, especially wet rock festivals. If you're deep in a mosh pit, and suddenly your wallet comes out of your trousers and falls into the mud, then you've essentially lost all your cash, cards and anything else you keep in it. Absolutele nightmare.
So Live Nation UK, which runs Download Festival, are experimenting with a form of cashless wristband that you 'charge up' in advance at the start of the festival, and then simply swipe your wrists over a scanner to buy food and drink, etc. I suspect there'd also be some form of top-up station, too - like an Oyster one, for when you overspend on the first day and run out of cash.
It'll be great for preventing theft (for both stall owners and punters) as well as helping combat drugs problems onsite - dealers aren't likely to have scanners. Any lost wristbands can be cancelled and replaced immediately with a new one with the same amount of cash on it.
Download Festival (via CMU Daily)