Here's my idea:
Create a user group for each console, make them available for forum members to join without approval, and voila -- an automatic list of who has what console.
Since it's possible to join multiple user groups, forum members could join each one that corresponds to a console they own.
It would be a simple, behind the scenes thing, but it would be a groovy way for people to keep track of who has what consoles. I suppose you could throw PC in there as a platform, too.