We like the idea of painting whole walls with blackboard paint; it's the closest most of us will ever get to owning a Cy Twombly. Abacus Construction Index provides a good roundup of leading chalkboard paint manufacturers and suppliers, including Benjamin Moore and Blick Art Materials.
Below: A hallway via Light Locations.
Below: A living room from Domino.
Below: A dining room outside Boston by Christine Lane Interiors.
Below: A kitchen with a chalkboard wall from the portfolio of Minh + Wass.
Below: A kitchen from photographer Per Ranung, via Desire to Inspire.
Below: Kitchen from Belgian firm In Search Of.
Below: A kitchen from Marie Claire Maison
Below: Of course, if you don't feel like committing to painting an entire wall, a giant schoolroom blackboard will do nicely. Photo by Tim Evan-Cook.
Below: A door painted with chalkboard paint serves as a giant shopping list in this kitchen from Living Etc.
Below: Another door painted with chalkboard paint; via Living Etc.
Below: A board painted with blackboard paint from photographer Hotze.
Below: A kitchen art space.