Dannon is typically known for its yogurt products. There's Activia, which is supposed to keep your digestive system regular; DanActive, which is a yogurt drink that supports a healthy immune system; and Danimals, the kid-version yogurt drink designed to taste good and provide nutrients and other "good for kids" ingredients. Not long ago, I was buying bottled water by the case, and noticed the familiar logo of Dannon on one of the packages. I didn't think much of it because I consider Dannon a pretty legitimate brand; I purchased the Dannon water because it was cheapest at that time and place. It didn't taste different from any other bottled water I could have chosen. Dannon must have recognized that consumers are familiar with and trusting of their brand, thus making the bottled water industry a relatively safe market in which to extend to.
Eventually I came across Dannon Fluoride water bottles, which claims to be "Great for kids on the go!" The packaging also has a young kangaroo playing soccer - being an active kid, if you will. This targets both parents and kids. Parents want their children to drink more water, apparently fluoride is good for you, and it is made by Dannon, a trusted brand.
Dannon has done a much better job with brand extension than Kool-Aid. One reason is that they have not over-extended their brand like Kool-Aid seems to have done. Another reason is that Dannon seems to recognize which products to extend to; that is, what markets have the potential for success. Whereas Kool-Aid seems to extend to any product possible.