The rules on this page are from the USAH Junior Hockey Rules book for 2009.  They represent what I believe are the critical rules for a goalie to know in advance of taking the ice.

Rule 202 (c). No goalkeepers shall be entitled to exercise the privileges of Captain.

What this means: The goalie doesn't get to talk to the refs during the game.

Rule 203 (b) Each team shall be allowed one goalkeeper on the ice at one time. The goalkeeper may be removed and another player substituted. Such substitute shall not be permitted the privileges of the goalkeeper. A goalkeeper may be substituted for by another goalkeeper during play with full goalkeeper privileges. However, once a goalkeeper has been replaced by a substitute goalkeeper, he may not return to play until the next stoppage of play. For a violation, a bench minor penalty shall be assessed for illegal substitution

What this means: Two things.  One, if you pull the goalie and substitute a regular skater, he can't cover the puck in the crease with his hands. Second, you can't swap a goalie during play like a regular skater, you have to wait for a stop in play.

Rule 206 (b) If a goalkeeper sustains an injury or becomes ill he must be ready to resume play immediately or be replaced by a substitute goalkeeper. No additional time shall be allowed by the Referee for the purpose of enabling the injured or ill goalkeeper to resume his position. (See also Rule 205(e).)

What this means: They may not give the goalie extra time to regroup if they get hurt.  Nice, huh?

Rule 301 (b)  In the case of a goalkeeper’s stick, there shall be a knob of light-colored tape or some other protective material approved by the League. Failure to comply with this provision of the rule will result in the goalkeeper’s stick being deemed unfit for play. The goalkeeper’s stick must be changed without the application of a minor penalty.

What this means: The tape you wrap around the top of your stick isn't just for making it easier for you to pickup your stick when you drop it, or to prevent it from getting stuck in the net, it's also to prevent injuries to other players in case you jab them with it.

Rule 303 (c) If when the goalkeeper assumes the normal crouch position, the shoulder and/or shoulder cap protection is pushed above the contour of the shoulder, the chest pad will be considered illegal.

What this means: If you buy a chest protector that is obviously too big for your child/goalie and it pushes up when they crouch down, it can be considered illegal.

Rule 304 (a) If the goalkeeper’s helmet/facemask comes off during play, the Referee shall stop play immediately. A minor penalty shall be assessed a goalkeeper who deliberately removes his helmet/facemask during play.

What this means: Refs need to stop play when a goalies mask comes off, but if you do it intentionally they can assess a penalty.

Rule 305 (c) No player or goalkeeper shall be permitted on the ice while wearing jewelry unless it is completely covered by equipment or taped to the body.

What this means: No bling for you.

Rule 406 (a) Penalty Shot. Once the player taking the shot has touched the puck, it must be kept in motion towards the opponent’s goal line and once it is shot the play shall be considered complete. No goal can be scored on a rebound of any kind and any time the puck crosses the goal line the shot shall be considered complete. Only a player designated as a goalkeeper, substitute goalkeeper or temporary goalkeeper (see Glossary) may defend against a penalty shot.

What this means: On a penalty shot, the shooter doesn't get rebounds.

Rule 406 (b) Penalty Shot. The goalkeeper must remain in his crease until the player taking the penalty shot has touched the puck and in the event of violation of this rule or any foul committed by a goalkeeper the Referee shall allow the shot to be taken and if the shot fails he shall permit the penalty shot to be taken again. The goalkeeper may attempt to stop the shot in any manner except by throwing his stick or any object, in which case a minor penalty shall be assessed to the goalkeeper, whether or not a goal is scored on the penalty shot.

What this means: Stay in the crease until the shooter touches the puck.  Marty Turco faces to the side before a shooter starts I guess so that the shooter will have a harder time determining which route (left, straight, right) to take.

Rule 407 (c) A minor penalty shall be imposed on a goalkeeper who leaves the immediate vicinity of his crease during an altercation.

What this means: If you leave your crease during a fight they can assess a penalty to you.

Rule 407 (d) If a goalkeeper deliberately participates in the play in any manner when he is beyond the center red line, a minor penalty shall be imposed upon him.

What this means: You have to stay on your side.

Rule 605 (a) A goalkeeper whose stick is broken may not go to the players’ bench for a replacement during a stoppage of play, but must receive his stick from a teammate.

What this means: If a goalie breaks their stick, they have to drop it like other players.  Best to have a player hand you one of their sticks until you can get a replacement.

Rule 609 (c)  A minor penalty shall be imposed on any player (including a goalkeeper) who delays the game by deliberately displacing a goal post from its normal position. The Referee or Linesmen shall stop play immediately when a goal post has been displaced. If the defending team has deliberately displaced the goal post, thereby depriving the attacking team of an immediate and reasonable scoring opportunity, or if, during the course of a break-away the goalkeeper deliberately removes his helmet/facemask, a penalty shot/optional minor penalty shall be awarded to the nonoffending team, which shot shall be taken by the player last in possession of the puck.

What this means: If it looks like you or a teammate deliberately moves the goal out of position when an attacker has a chance to score, they can be awarded a penalty shot.

Rule 609 (c)  If a minor penalty for deliberately displacing a goal, or for the goalkeeper deliberately removing his helmet/facemask during play, is assessed with less than two minutes remaining in regulation time, or at any time during overtime, a penalty shot/optional minor shall be assessed against the offending team in lieu of the minor penalty.

What this means:  Try not to take a delay of game penalty in the last two minutes of the game.

Rule 614 deals with goals, there are quite a few, but I think most are well known.  I will comment on the less well known ones.

Rule 614 (e) If a goal is scored as a result of a puck being deflected directly into the goal from an Official, the goal shall not be allowed.

What this means: A puck redirected off an official doesn't count as a goal.

Rule 615 (a)  If a player, except a goalkeeper, closes his hand on the puck, play shall be stopped and a face-off shall follow; however, if the puck is dropped to the ice immediately, play shall not be stopped. If a goalkeeper holds the puck with his hand for more than three seconds, play shall be stopped and a faceoff shall follow; however, after an initial warning by the Referee, a goalkeeper who holds the puck unnecessarily shall be assessed a minor penalty for delay of game.

What this means:  If the ref tells you to play the puck after you cover it, you should look for a safe way to put it back in play or risk a penalty.

Rule 615 (b)  A goalkeeper shall not drop the puck into his pads or onto the goal net, nor deliberately pile up snow or obstacles at or near his goal that, in the opinion of the Referee, would tend to prevent the scoring of a goal. The penalty for infringement of this rule by the goalkeeper shall be a minor penalty. 

What this means: Watch the snow buildup in front of your net.  As a butterfly goalie, I try to clear the snow frequently anyway.

Rule 615 (c) If a goalkeeper catches the puck and throws it forward towards his opponent’s goal and it is first played by a teammate, play shall be stopped and the ensuing face-off shall be held at the nearest end face-off spot of the offending team. See also Rule 615(e).

What this means: If you catch the puck in your glove and want to put it back in play, don't send it toward the other goal (too far).

Rule 621 (c) When the puck is in the Attacking Zone and not in the goal crease, a player of the attacking team may not stand on the goal crease line or in the goal crease, hold his stick in the goal crease or skate through the goal crease. If the puck should enter the goal while such a condition prevails, a goal shall not be allowed. For violation of this rule, while the attacking team has possession of the puck, play shall be stopped and a faceoff held at the nearest Neutral Zone face-off spot. (Note) This rule shall not apply when the goalkeeper is out of his goal crease.

What this means: Refs are supposed to disallow goals when a player from the other team is in the crease before the puck crosses into the crease.   Good luck in getting them to call it consistently.

Rule 627 (b) When the puck is in the Attacking Zone and not in the goal crease, a player of the attacking team may not stand on the goal crease line or in the goal crease, hold his stick in the goal crease or skate through the goal crease. If the puck should enter the goal while such a condition prevails, a goal shall not be allowed. For violation of this rule, while the attacking team has possession of the puck, play shall be stopped and a faceoff held at the nearest Neutral Zone face-off spot. (Note) This rule shall not apply when the goalkeeper is out of his goal crease.

What this means: If there is a delayed penalty against your team, just hitting the puck with your pads doesn't constitute a change of possession so the refs don't have to blow the whistle.