Calves, unfortunately, are about 90% genetics. lol
But you can help them along somewhat - try jumping rope, jumping jacks (good for cardio intervals!) and even some plyometrics. Anything requiring explosive running/jumping type movements will help calf development.
I (thank god!) am very blessed with calves, but have NEVER goitten anything out of those toe rasie machines at the gym (besides a compressed spine, lol). I'd rather do jumping rode, and plyo's.