I'll probably think of more "unusual" things, but...

- a bunch of Apple sales brochures from the early 90s.

- an Apple Peripheral Interface Guide (describes all the cables/ports etc - quite handy)

- a few unopened internal modems for PowerMac 5200/6200 machines (Aus spec)

- an original Apple 300/1275 baud modem

- a proper Ethernet to LocalTalk router ("EtherRoute TCP")

- [edit] an old HyperDrive board too