I second this suggestion. I could use a whole multi-season series *just* on ビジネス日本語, 尊敬語, and 謙譲語 in an Intermediate/Upper Intermediate level style (all in Japanese, minimal English). You could cover the entire spectrum, from 就職活動 to the 退職のパーティ, with everything in-between. There are so many grammatical and cultural minefields to avoid, I need all the help I can get!
I really liked the Upper Beginner series last year on announcements using polite language, but that's really just the tip of the iceberg.
I know there are already lessons on business Japanese here and there on the website, but that's the problem: they're here and there, and not all in one place. Some are beginner, some are upper beginner, some are intermediate, etc. It would be nice to just have one series devoted for business use. (And it would be a great marketing tool!)
Some areas I'd love to see covered: networking, job interviews, getting hired and dealing with joining the company, negotiating salary, getting paid, answering the phone, handling troublesome tasks, visiting other companies, politely declining invitations (or accepting them), dealing with the boss, dealing with the boss' boss, dealing with customers, dealing with suppliers, quitting, retiring... so many areas. @_@