Copyright-free posters for peace
Graphic design legend Milton Glaser is perhaps best known for his Bob Dylan poster and I Love NY (and I Love NY More Than Ever) logoes. The above image by Glaser is part of the Another Poster for Peace project, a downloadable & printable online collection of "copy-right free art for public use."
While you're at it, get some copies of the Deception Dollar (below). This crappy web image really doesn't do it justice--you need to look at a two-sided print copy (handed out at the Manhattan peace march this weekend) with a magnifying glass to see all the tiny oil wells and Enron and Halliburton symbols.
And for anti-war songs and videos (among other things), see the Artist's Network of Refuse and Resist.