I've seen this requested a few times, but there haven't been any culture lessons for ages. With the limitations of the format, it would probably take them forever to cover it to a usable level. You might find these books to be of interest:
Depending on your level, it might not be a good idea to get too far into it, since you might end up having difficulties drawing the line between kokugo and dialect. I think I'd like to learn some at some point.