Rao's professional barista handbook is a very good one to have in your shop. It would be nice if you could buy a couple of copies and lend them out to your barista's. They are sort of steep though for books (as are most). Kenneth Davids books are pretty standard as well. They are more affordable ($9-13) but a bit on the dry side with heavy reading; an exceptional resource nonetheless.
If you're looking for a good movie to showcase the general process of coffee I would recommend the "Passionate Harvest", which is an excellent visual account of coffee though still a bit on the expensive side ($80+). I would recommend that if you would like something to show your barista's.
Also, check out this thread that mentions a whole heap of excellent coffee books:
I apologize for this seemingly self-plug (I wrote it) but I think The Hawaii Coffee Book- A Gourmet's Guide from Kona to Kauai is an incredibly comprehensive book that starts with planting and goes through every step of the process, right up to drinking and ethical issues. It does so using Hawaii as a case study, if you will. I think it is the only consumer-friendly book that covers so much of the coffee process. If I'm wrong, I'd love to hear what other titles are out there!
Don't let the title or cover fool you! It is way more than a silly touristy book! If you want to learn about everything that happens at origin with coffee, this is a great way to learn about the basics. (Note, it is not designed to be technical like Wintgen's excellent book.) It is pretty accessible and written for folks who don't know much.
Best yet, it is pretty cheap on Amazon (~$12). I'll sign and ship it to you but it will cost a bit more... :-)
I'd also add to the list: The Coffee Book: Anatomy of an Industry from Crop to the Last Drop by Gregory Dicum and Nina Luttinger. I can't remember if it made it to the other list that Brown linked to.