This might not be new to anyone, but one of my Christmas gifts this year was a neat reproduction of a WPA poster:
I didn't know these posters were available, but apparently, since they are public domain, they are all over the place. The Library of Congress has the main archive (these are fun), and many people reuse the artwork to sell posters, bags, and just about anything else.
So, I get a fun poster out of the deal, but the real message is this: putting things into the public domain does not stifle commerce; absurdly-restrictive copyright does.
Oh yeah, I forgot to include this link: Vintage Ads for Libraries and Reading - more good stuff. Thanks again, Tommy.