I love graphic design, especially design that serves a function or evokes some reaction from its message. Here are some that are free to use that I have found from resources that I love!
Some inspiring Depression-era re-posters here!
This campaign at Things are fine is controversial
but powerful and in the a graphic design sense, extremely effective!
I found this resource through the ISO50 blog (a great design resource!)
The source of this and other jaw-dropping poster scans can be found here.
Well, to lighten the mood:
This site is an amazing vintage poster resource!! Thought this one was fitting
and rather bizarre for the season!! Dear Santa, please don't drink and drive on X-mas!
Ho ho ho!