Come on now... Like what is the US equivalent of say:
http://www.roberthorne.co.uk
Mohawkhttp://www.mohawkconnects.com/
Monadnockhttp://www.mpm.com/
Two of my favorites.
I remember seeing a giant cabinet filled with paper sample books from a place called Xpedx. They always sent us books free.
http://www.neenahpaper.com