I am a big fan of the old Infocom games and as of late I've been trying to find all the oddball items.
Posters,maps,T-shirts,promotional material,buttons,employee items, anything released by the Zork user groups. In general if you have something that a person could not walk into the store and buy even when it was current then I am looking for it.
Here are a few of the things I found pictures of online.
Early Zork color poster
Another Zork Poster
Zork I Zork user group (ZUG) maps on pachment paper
Zork II ZUG map
Zork III ZUG map
ZUG Starcoss map
ZUG Deadline map
Infocom brass 5th anniversary card & Hitchhikers Guide to the Galaxy business card case