Gorilla Milk ad, from the super-cool Flickr group run by the guys behind Krazy Kids Food (check out this book if you have any love for retro ads ... so awesome)
Also, Drink Aid (Ape Grape! Rhino Raspberry!) looks like a lesser-known version of Funny Face drink mix (from Minnesota's own Pillsbury).
And don't forget Nestle's drink-mix foray, Keen Chiller. Which I guess is supposed to be scary, but I would not have guessed that if not for the stereotypical Halloweeny monster font.
It's funny, we were just talking about how rarely we drank soft drinks as kids. Even on that occasional visit to McDonald's we had to have their "orange drink," which apparently was supposed to be better for you (did it contain orange juice? I dunno...). So in a world in which soft drinks were not everywhere, especially for kids, these powder mixes flourished.
Just another tiny sign of a time gone by.