How do I keep yellow corn stone ground grits creamy for an extended period of time?

microwave works fine for us to reheat creamy grits.

My sister makes hers in a slow cooker. She cooks them overnight using milk as the liquid. On low. She swears they are the best grits ever

A lot of people swear by the double-boiler method for polenta, which allows you to hold it for several hours and makes the polenta extra creamy -- grits should work in pretty much the same fashion. Here's more on the subject: http://orangette.blogspot.com/2010/02/reasonable-question.html