Petr Pos - Czech Ghostbusters Poster, 1988
An article on Contemporary Czech and Slovak poster design can be read here, with a small sample of art by Pos.
Also, a tattered copy of a book titled "Making Ghostbusters" recently came into my possession which includes the original script, many photos and most importantly, a fantastic array of conceptual art used for all the ghosts and bizarre creatures created for the film. Many of these abominations do not appear in the movie due to budget restraints. I'll be scanning these and sharing them with you later this summer, until then you can enjoy one of those artworks which I found last year.
And check out this awesome cut out scene.