As far as I remember, I've always been interested by science. Sometimes, there is a few topics discussing it in the the Off-topic section, but this is always a bit sad and not really interesting. Creating a science subsection could allow people to discuss the big progress that is currently being made in astronomy, or everthing that is going on the scientists' planet ! A science subsection is definitly a good idea I think. It would be my 3rd favourite.
I love reading, and since I know how to read, I red a lot of differents books, of different kinds. Literature is something important for us, this is about culture. Sadly, no one is talking abiut this. There could be some interesting topics, discussing about the books that everyone red. One could make a suggestion, that could make people read this book, and then discuss about it. The creation of a literature subsection, could be benefical to everyone to escape from the numbers and discuss about masterpieces or common books. It would be my 2nd favourite.
Music is something that everyone loves (there's some exception), so a dedicated subsection could make people discuss about it. Since this is the suggestion of the subsection that I like the least, I have not that much arguments to defend it. This would be my least favourite.
History, one of my biggest passions in life ! An history subsection could allow some people to post topics about a precise domain. People could instruct themselves without leaving Bitcointalk ! There's nothing I can like more, this would be like a dream. This is my favourite hypothetical subsection.
All this subsections could be condensated in one big subsections, called the cultural subsection. This cultural subsection could be located in the "Other" board, or could have it's own. Tell me what you think about it

! I greatly hope that it will exist someday !