Here are a few of my favourite links

http://www.degournay.com/
Silk chinoiserie style wallcoverings. Have a look at the new Chinese dining room of the Park Lane Dorchester for a stunning example of de Gornay silk.

http://www.fromental.co.uk/
More fabulous Chinese silk. Fromental does different take on Chinese silk with the addition of a hand embroidered element. Check out the bar next to the Dorchester Chinese restaurant, to see Fromental next to its rival.

http://www.jocelynwarner.com/
Sophisticated, striking modern design.
Intelligent design for the discerning client.

http://www.wallpaperdirect.co.uk/
Its all here, and they are good at sending out samples.

http://www.cole-and-son.com/new_collections.asp
Long established English firm. A wide range of beautiful paper.
Nice modern stuff including some gorgeous metalics.

http://www.wallpaperinstaller.com/residential_wallpaper.html
Best Wallpaper hangers site on the web. U.S based but good links
to sources world-wide.