You may want to consult the Laws of The Game, and always remember Law 18 (Common Sense!)
A great site for asking questions and getting answers is asktheref.com. This is a fun site!
Michael Kopinski also sent along a couple of other sites which might interest you. Official Sports in the UK runs the Referee Forum, which includes a USSF section. Rate the Ref is another English site, which has the unique feature of having ratings done on the Internet.
Oh crap, we're a man short!
You stop a game for an injury and the player leaves the field, but no substitution is made, so the player's is playing with only ten men.
A minute or so later an opposing player gets a breakaway. As he is going to goal unopposed the injured player reenters the field and cleanly steals the ball from him. No foul is committed. What, if anything, do you do?
Click here for the answer and explanation
Reaching for the Sky
During a game you award a goal kick to the home team. Well before the kick is taken, one of the opposing players stands in the center circle and holds his hand straight up in the air and leaves it there. When the kick is taken it hits this player on the arm.
Is this a hand ball?
Click here for the answer and explanation
The Streaking Spectator
This appeared in a recent issue of Soccer America.
During a men's adult game in England a spectator ran onto the field in all his glory. While this well may have been more entertaining than the game itself, the players took a dim view of this action and one of them tackled the spectator, who was subsequently removed from the field by the authorities.
As the Referee, what would you have done when the spectator entered the field?
Click here for the answer and explanation.
Kicking for Three
This happened in a recent Boy's State Cup, refereed by yours truly.
Near the end of the game, which was played on a very windy day, a goal kick was awarded to the team kicking into the wind. The goalie placed the ball in the Goal Box and held it down with his finger while his teammate took the goal kick.
While this was well done for a Field Goal attempt in American Football, it certainly looks wrong in a soccer game, but what do you do, if anything?