I recently made these chalkboard seating cards for a surprise dinner party at a friend's house. The process is fairly simple, all you need is some unfinished wood tags (you can find these at a crafts store like Michael's), chalkboard craft paint (Martha Stewart makes a great one), a paint brush, and a white pen or chalk.
Start by painting the wood tags with the chalkboard paint. You will probably need at least 2 coasts in order to get good coverage. Paint the back and sides too. While the tags are drying it might be a good idea to practice your calligraphy. If your handwriting isn't stellar, you can find a nice calligraphy font online and enter your own custom text to see how it would look. Use a pencil to lightly write each name, and when you're happy with the way it looks go ahead and use the white pen or chalk. I used a white pen for a more formal look, but chalk works well too. Just tie the tags around each napkin using a natural twine, bakers twine, or other sting. Voila! At this particular dinner party, not everyone knew each other so we all wore the name cards like a necklace during dinner. It was a great icebreaker, and actually quite helpful!
First image by Ashley, all other images by Jonah Fuller. (Thanks Jonah!)