I have a few that may be called "trivial":
1) I let Monks and Paladins multiclass freely.
2) I ruled that you cannot 5' step diagonal "through" a blocked square. For example if you are just past the corner of a wall, you cannot 5' step "diagonally" to the other side of the corner. On this rule, any square occupied by an enemy is considered "blocked" and in order to 5' diagonally around them, you must make a tumble (DC 15) check.
3) Protection from Evil gives the AC and Save bonus and prevents control, but does not prevent bodily contact from summoned creatures.
4) If you are taking too long to decide what to do on a combat round, I start the stopwatch. If you havent acted after a minute, you pass your turn.
5) Dont roll a saving throw unless the DM is ready to witness the roll.
6) Double headed weapons gain the bonus for weilding a weapon with two regardless of which head is used (normal rule is: 1.5 strength on 1 head and 0.5 strength on other head, like two weapon fighting). I did this to try an make two-headed weapons more "desirable", but still no one uses two -headed weapons.
7) When making potions and scrolls, you can create a number of items up to 1000gp/cost per day to a maximum of 5 (example, it takes 1 day to make 3 300gp scrolls or 1 day to make 5 100gp potions).
8) Medium armor has no movement penalty.
This is just what I consider the "trivial" stuff. I must be really picky!