Thought I'd up the ante a bit and post some of my stuff. Can't believe I haven't posted any of these in here earlier.
Mega Man 2 proto with "Clash Man"
Gargoyle's Quest II and Street Fighter 2010
Mappy-Land Proto
Low G Man Proto
Kartoon Kombat for Genesis on 3.5" Floppy (unreleased) and Hoppin' mad for NES (unreleased)
Caesar's Palace Proto
Blues Brothers Proto
Arcadia VI proto (unreleased)
Hatris and Bases Loaded 2 Protos
Several Pitfall SNES and Genesis protos (one of each VERY different than the released version) and 9 different builds of a GB Boxing game
Bubsy II Proto
SNES MK3 Proto chips
Krazy Kreatures Proto
Super Turrican NTSC chips (unreleased)
Darkman Proto
Ninja Gaiden III
Tengen Pac-Man Proto
Vectorman 2 Proto
Kitty's Catch Proto (unreleased)
Super Talking Jeopardy! Proto on a super cool Atari (Not Tengen!) board
Road Runner Proto:
Solar Jetman Proto:
Boulderdash Proto:
Archon Proto:
Mag Max NES Proto:
Magic Darts NES Proto:
S.C.A.T. NES Proto:
Very Early Monster in Pocket Proto:
Spy vs Spy 2: The Island Caper unreleased proto:
Zombie Nation Proto:
Alpha Mission Proto:
Caveman Ninja NTSC Proto (Not Euro as the label states, unreleased in this format:
Castelian Proto:
Solomon's Key 2 NTSC Proto (Unreleased)
Ikari Warriors II Proto:
RamPart Proto:
I have at least 2 more here not listed, and another cool one in (and a loose board for the Super Turrican chips) in the mail. I'll make sure to update.