Antoinette J. Citizen did an amazing, amazing thing. Her(?) intallation of "Landscape" has all of the Nintendo Super Mario Bros. background, as well as interactive question mark boxes. And, it's so popular, that her site seems to have gone down while I was typing this... :( Hopefully it will come back up. But I love this so much. It seriously made my day.
Farrow & Ball offer free wallpaper samples. They have a really classic feel and tend to work in a neutral pallet.
Only 2 free samples per order.
Free paint samples. Not paint chips. Not fan decks. FREE PAINT. Visit Freshaire choice paint's web page, choose three samples, call their toll-free number, and receive 2-oz samples by mail.
Their paint is also VOC-free, which means it's environmentally friendly, and their packaging is 100% recyclable.
Lonseal is a vinyl designer and manufacturer that "pushes the limit" of vinyl convention. Although their products are mostly for commercial use, they have some really interesting designs. It reminds me of industrial in the future. They also have earth-friendly products in their Greenvinyl program.
Armstrong commercial floorings in the US provides free samples, although they charge a shipping and handling charge. 
Anderson Hardwood Floors are very accomodating with their free samples and they have hundreds of styles to choose from. You can order 4 samples at a time and they offer free USPS shipping.
