Many people like the idea of soda fountains, but the official fountains that mix soda and pre-mix concentrate are quite expensive and work to maintain.
To gain some of the convenience and efficiency, how about a quasi-real fountain using existing 2-liter pop bottles? Such a fountain would be designed to look like a regular one. Inside, ordinary 2-liter bottles would be attached. In a "party" model, they would just be in an icebox, in a full-time model it would have refrigeration.