Ghostbusters and Alien posters by Tristan Jones. The Alien poster is on sale here.
Mike Maihack posted the cover and interior illustrations for Geeks, Girls, and Secret Identities, which is available at Amazon.
Three by Yefim Kligerman. (The first reminds me of Julia from The Magician King.)
Glow in the dark Beetlejuice poster by Anthony Petrie on sale here.
*Buy Beetlejuice toys at eBay.