The main store sells minor items, bread, peanut butter, dounuts, chips, I think milk & ceral and a few cold things too. Resorts that have DVC in them seem to sell a bit more (like WL and BC.)
There is a places that delivers for $15 from any store you want. I think the site is wegoshop.com but I am not sure. There is a thread about it on the DVC site.
All rooms at POR do now have refridgerators in them now.