The Bicycle Automatic Card Shuffler is a battery-powered card shuffler that can shuffle several decks of cards quickly.
This card shuffler is fairly inexpensive, but you get what you pay for. It requires a 9 Volt battery for operation. You load half the deck (or decks, for multiple decks) into one side, half into the other, and hold down a button while the cards are shot into the center, one from each side. A removable tray allows you to take the cards out and begin using them. It will shuffle large or small cards, one deck or several.
It's quite noisy when you use it. In fact, it will often drown out the voices of others around, and should probably be used only if you don't know how to shuffle or have a physical disability that makes it overly difficult to shuffle by yourself. Cards frequently get stuck or left behind, so several uses of the shuffler should be used to insure a good shuffling.
It's made of plastic and seems quite flimsy, but mine has held up through a decent amount of usage. If you're looking to speed up a game by using an automatic shuffler, this won't work. It takes too much time to load, shuffle, unload, etc. I highly recommend getting a second deck if you're a poker player, whether or not you use this shuffler.