I'd like to see them release a library ghost in both "normal" and "fright" formats. Also, I'd like to see a diorama-type scene, kind of like what they did with the "Spider-Man 3" teaser poster. I'd buy a 3-D poster like that from them.
I guess at this point, I'm more excited that the movie is getting some stuff out there and gaining some new fans. Five years ago, you couldn't find a darn thing other than something fan-made. Now, they are slowly starting to refill the market. I won't bother me if they only release a full-size Slimer or a miniature proton pack (with or without lights). I'm just glad that Ghostbusters is coming back and that there is some officially licensed stuff besides old 80s buttons and t-shirts.