My calves ain't too shabby so I'll chime in...
I agree with the mentioning of the different fiber types of the soloeus and the gastroc. I've always hit my gastroc (straight leg calf work) with heavy weights and lower reps, while targeting my soleus (bent knee calf work) with lighter weights and higher reps.
With both, I've always stressed a hard contraction held for a second, and slower negative. Additionally, I never bounce out of the bottom of the movement, which I feel just kills a lot of the stress on the muscles, and can actually lead to plantar faciitis (probably spelled incorrectly, but I've had it several times and it truly sucks!).
Lastly, I will note that once I started training each muscle of the calves on different days (divide and conquor), my calves actually started growing. Nowadays, I do straight leg calf work after chest, and bent leg calf work after upper legs. Works like a charm