This sounds like the most interesting request I've seen in a while. "Ask your concierge to find or order a book for me." I remember trying to find a really obscure book that I read as a child, "(Abraham) Lincoln's Yarns and Stories". I found a copy in Powell's Book's in Portland, OR. Now you can get it on Kindle for free.

I always think of using concierges for local things, tickets for plays, advice on restaurants, local bookstores, buying flowers, etc. I would not think to ask them about buying books online.