Suggestion: Create a few header images for each board (or invite other people to create them, I think this is what Squeeks did aeons ago) and make them randomly rotate with each visit to the webpage. Include the current header images in the rotation if you don't think them being labeled with the names of different, nonexistent boards would be confusing.

That way Hobbies can still have food header images. The current Film & TV one is pretty cool too.