DoggoneGood!: Portable Water Bottle Device
From doggonegood.com: Portable drinking device attaches to the top of a standard water bottle; when the dog licks the "roller ball" mechanism it releases water. It is neat, doesn't waste water, and no more squeezing the bottle and "shooting" water into your dog's mouth and making him choke! Most dogs learn it very quickly and are happy to use it (you know how sometime you fill your hand with water and your dog just looks at you like "right, like I'm going to lick water out of your hand").