I'll kick it off. My three changes:
1. Outlaw headshots
I would remove all of the ambiguity of the current rule currently in place, and totally outlaw hits to the head. Was it from behind? Was it from the side? Was the player looking? It shouldn't matter. This is a matter of player safety, with serious long term and debilitating effects to consider.
Improvement to the game:
The game (and the lives of its participants) would be improved by reducing the number of head injuries.
And don't give me that "you need to keep your head up like they did in the 60s, 70s and 90s" business. The players weren't remotely as big, strong and as fast they are now. They didn't wear padding which serves nicely as a weapon, and the game itself didn't occur at close to the pace it does today. Also, we didn't know then what we know now about concussions.
2. Reduce roster sizes by 1
If you were an NHL coach, and were only allowed to dress 17 skaters instead of 18, which of the bottom guys on the roster would you get rid of: the AHL tweener who can play a bit, or a goon like Steve MacIntyre, who can't play more than a few minutes per night? I'll tell you the most likely answer based on what the league was like before 18 man rosters: the Steve MacIntyre/Stu Grimson/Eric Godard/Trevor Gillies/etc type of player is history.
Improvement to the game:
The game would be better off with a big pile of non-NHL players not being in the NHL. Think of major league baseball clubs dressing players that can't hit or throw remotely close to the major league level. Think of NBA teams carrying players that can't dribble the ball or shoot close to the hoop. Think of an NFL team dressing a receiver that can't catch the ball...
Additionally, this would represent salary cap space better directed to guys who can, you know, PLAY HOCKEY.
3. Implement tougher drug testing
It's obvious that the drug testing currently in place is a joke:
-players are not tested in the off-season, which is the time of greatest benefit for PEDs like steroids. Since the program greatly concentrates on testing for steroids, not testing in the off-season won't catch very many cheaters.
-looking at what hasn't been banned is also interesting, such as rigs used to assist players in passing urine tests.
-players are also not tested for any stimulants, so PEDs like ephedrine are completely fine.
-the blood test administered to the players doesn't detect HGH use.
-players are not tested at all during the playoffs.
Improvement to the game:
It's tough to put into words, but really can only arrive at a lame message, like "at least the league would be *trying* to keep its players honest. Is the league any better off by basically looking the other way? I don't think so.
Daryl