Option 1:

After each round the winning team would get to select one player from the losing team to add to their roster. This player would not count against the salary cap and would go back to their original team by the end of the season. The would allow the finals to be two all star teams going at it! You could even add in extra rules on top of this like if an underdog team wins they get two players, you can only pick one player for each position (forward, defender, goalie), etc.

This would create absolute chaos as the playoffs continued but I think ultimately it would take away from the team unity having all these players join last minute. It may feel they did "earn" their victory at the end of things. That said, doing something like this for a mini-tourny in place of the all star game could be an option.

(Oh! And an extra puck per OT period would be chaos too! So 2 pucks the first OT, 3 in the second OT, etc.)