My favorite poster (and shirt) was from the first PPE, which I didn't attend. Normally I won't buy a shirt or poster unless I attend the event, but I made a huge exception for these.
The art was done by Dan Fontes, who is an artist that is on the PPE board and a hell of a nice guy. Occasionally hosts tournaments at his home. He told me that he had very specific instructions given for the poster. To me, it looks like a cross between a 60/70's concert poster from the bay area and what the posters for the San Francisco Exposition (Worlds Fair) held on nearby Treasure Island in 1939 might look like. I have a poster framed and it's on the wall in my living room. Pic below doesn't really do it justice, but you get the idea.