Unsurprisingly, I used to have a huge collection of silk-screened revolutionary posters lining my walls. The Emiliano Zapata one was probably the most beautiful, but there was a terrifying one from the MIR in Chile. It was on a ~4 foot high, torn-off piece of newsprint, spray-painted through a stencil, and showing a stylized naked man in a stress position, hanging in mid-air with his hands tied behind his back.
Selling silk-screened posters was one of our primary means of fund-raising at speaking events and big demonstrations. Sadly, they all went into the dumpster years ago. The art form has proven to be sufficiently ephemeral that I can't even find images of any of the posters that I used to own.