Andrew,
Good to hear from you and that you are getting into the MMA.
My philosophy is that all muscles are important to work and be strong. maybe the calf helps with a takedown or creating lift in a throw, maybe it helps in keeping you on your toes later in a fight, maybe it helps in prevention of a foot lock until you escape. In any case, I think they are important to work not just for calf health, but also the foot health that results too. (for more on that, check my audio interview on this site).

We do our lunge work barefooted which is a new challenge to the calves and feet and can spice up your session.
Classic calf raises (although not sexy) are also important and donkey calf work is important too since the soleus needs work too.
We also now do sets of 50 calf raises for 3 sets before judo. Try that on for size and you wont walk for days. The sensei had us also do 300 straight reps with just bodyweight. I was sore for a week.

I hope this helps.

,
Martin Rooney