I'm the H&S officer at work and we bypass our marketing people entirely when it comes to the majority of signage, I find the office staff themselves tend to come up with better ideas than marketing folk and its then in their language and it's their sign in effect.
Once a design and slogan has been decided we use this place:
http://www.diginate.com/ where you can desing you own custom signs, I think they are all sticky backed though but would could mount it on a board?
Just an idea?