A newly updated version of the Ecological Guide to Paper, by Celery Design, has been released. It's aimed mostly at publishers, but is useful to any company sending out a newsletter, annual report, or what have you, so mention it to whoever you work for.
It's sort of a catalog of tree-free and recycled papers, but instead of listing prices it lists eco-characteristics. And there are papers for every price range included, not just fancy expensive ones.