So right now when viewing a game page, you can click the Collections tab to view all other users that currently have that game in their collection. My suggestion is to add the Cart/Disc, Case/Box, Manual and Other Inserts information check boxes to this as their own columns.
Current design:
Username Added Messege
Person 1 Date Button
Suggested design:
Username Added Cart/Disc Case/Box Manual Other Inserts Messege
Person 1 Date X X X X Button
Person 2 Date X O X O Button
Person 2 Date X O O O Button
It would use the same checkbox graphic as the game info panel on the right side of screen when viewing your collection. Maybe take this one step further and allow these columns to be switched ascending/descending so you can find someone with something specific. Or add a toggle option to the user's profile to hide this information.