this discussion has been a real eye opener! I bought one of those things cuz the cute salesgirl said it was a 'personal butter maker'. I put milk in it and spun the hell out of it, but all i ever got was wet.
I literally just thought the other day about using a grinder for certain pipe tobaccos. Glad to hear it works as expected. Some of those plugs with the big full leaves of tobacco are a royal pain in the ass to rub out.