Well, even though it will probably never happen... I'd LOVE to have different kinds of dolphins! My favorites are the orca and bottlenose. They would be so neat to have!
As for realistic ideas, I'd like a puppy, horse, bunny, goat, duck, ferret, parrotlet, turtle, and fish. I already have two cats, and 7 hamsters. (Uh, one just had babies... >_>)