Yep. I personally use spackle from Home Depot, though different people use different stuff.
I find the spackle to be ideal: dries fairly fast (1-2 hours), is hard enough to take some light modding on top of it (but isn't strong enough to support off-balance minis...for that, I use super sculpey), is easy to apply and isn't toxic, and if I mess up it isn't too hard to remove.