From the August 12, 1906 NYT:

Many of the rules [of college football] have been changed and others thoroughly explained, with the double object of eliminating brutality and making the game more interesting to spectators. Of the many changes, the most radical has been the introduction of the forward pass.

The necessary distance to be gained in three downs has been doubled - that is, the side in possession of the ball must gain ten yards in three downs instead of five...This is the most direct legislation against mass plays, and is intended to make the game more open.

The time of the game has been shortened by ten minutes, making the two halves each thirty minutes in length.

Hurdling is defined and forbidden. Hurdling in the open is jumping over or attempting to jump over an opponent who is still on his feet.

There must be always at least six men of the side in possession of the ball on the line of scrimmage, and if only six are on the line one of those not on the line must have both feet outside the outside foot of the player on the end of the line.

The definition of holding, which in the past has been productive of much wrangling, is more clearly defined, and includes: Grasping an opponent with hands and arms, placing the hands on an opponent to push him away from the play, circling in any degree any part of the opponent with an arm.

Sports leagues can provide public goods such as rules changes that make the game more entertaining and safe at the same time. College football suffered more than 100 deaths during the 1905 season. These rules changes were a direct response to these deaths and the threatened abandonment of the game altogether.

Thankfully, as professional and college football is (still!) right around the corner, rules changes of these ilk were instituted.

From Scout.com the article "NFL Rule changes for 2006" posted on August 12, 2006:

Down by contact calls may be reviewed by instant replay. Reason for the change: Provides a mechanism for correcting an obvious on-field officiating error.

Each instant replay review will be a maximum of 60 seconds in length. Reason for the change: Shortens game length.

Individual players are prohibited from using foreign objects or the football while celebrating. Reason for the change: Promotes sportsmanship.

If possible, rushing defenders must make a conscious effort to avoid low hits on the quarterback. Reason for the change: Player safety.

The prohibition against blocking in the back above the waist applies to a player of the kicking team while the ball is in flight during a scrimmage kick. Reason for the change: Player safety.

All players are prohibited from grabbing the inside collar of the back of the shoulder pads or jersey, or the inside collar of the side of the shoulder pads or jersey, and immediately pulling down the runner. Reason for the change: Player safety.

During a field goal attempt or a PAT, any defensive player within one yard of the line of scrimmage at the snap must have his helmet outside the snapper’s shoulder pad. This will provide protection to the snapper, who is in a defenseless position. Reason for the change: Player safety.

No more than six players can line up on the same side of a formation on a kickoff. Reason for the change: Player safety.

If there is a personal foul...that occurs between the end of the second period and the beginning of the third period (or between the end of the fourth and beginning of OT), the penalty shall be enforced on ensuing kickoff. Reason for the change: Provides uniform enforcement for personal or unsportsmanlike conduct fouls throughout the game.

If there is a foul during a scrimmage kick or a free kick prior to a player of the receiving team securing possession of the ball, the offended team will have the option of taking the penalty at the previous spot. Reason for the change: Eliminates re-kicks.

If an offensive foul is a foul by the kicking team prior to a player of the receiving team securing possession of the ball during a down in which there is a safety kick, scrimmage kick, or free kick, the period may be extended by an untimed down, if the defense accepts the penalty. Reason for change: Eliminates fouling to obtain an unfair advantage.

Teams can now opt to take the result of the play OR replay the down when there is an inadvertent whistle. Reason for the change: Current rule too punitive.

Some of these are modifications to existing rules, such as the horse-collaring rule. To the extent that modifications are made to improve player safety while not dramatically altering the quality of play, these decisions are examples of how centralized decision making can be welfare enhancing, i.e., it can make players, fans, and owners all better off, and are very similar to the rules changes of 1906.

Personally, I like the carryover of personal fouls from the end of the half/regulation. It has always bothered me that a penalty thrown at the end of the half, say for taunting or other bad behavior, didn't carry any true punishment.

Although I am not a huge fan of instant replay, the professional (and increasingly the college) game is so fast and there are so few games that perhaps it is warranted relative to, say, professional baseball's regular season. An additional problem is the increasing cost to a bad call. It is entirely plausible that a bad call could be marginal in the sense that it could deny a team a post-season berth. In this case, the dollar cost of the bad call to the teams might be dramatic and justify the use of instant replay. This is why the instant replay is becoming more important in college football - a bad call could be the difference between a high pay-out bowl game and a low pay-out bowl game.

If high school football begins to generate significant revenues, be ready for instant replay at that level as well.