As I was watching the US win the hockey World Junior Championship (U20), I thought that it would be cool to have that team available to play in NHL 13. Couldn't the developers create teams to use? They already have the platform. It would be a matter of uploading the jersey design and creating the 20-25 players on the team.
This could easily extend to classic teams, like the 1980 Soviet or US Olympic teams, the Summit Series teams, famous Cup-winning teams, etc.
Of course, I have not checked into how much of this has already been done, so there likely will be people telling me so :)