Here's the list of sample Combat Maneuvers I handed out to my players. Players are free to try anything and come up with more such maneuvers, subject to DM approval. Anything approved, that is of general applicability, will be added to the list.
Charging: A creature who is more than 10’ away from their target, may Charge one time per
Turn, moving at double their normal movement rate and attacking in the same round. They
receive a +2 bonus to hit, but suffer a -1 penalty to their AC and lose any Dexterity bonus to
AC when charging. If the defender has a weapon which is longer than that of the attacker’s,
then the defender will attack first. Certain weapons (spears, lances and halberds) may be
“set” against a charge, and will inflict double damage if a hit is scored upon a charging
attacker. A rider upon a warhorse and wielding a lance, will do double damage for the
weapon, on a charge. A creature may not charge if they are at their maximum amount of
encumbrance, unless they are on a warhorse which is not at its maximum encumbrance.
Close To Attack: Unless charging, a Character may close to within melee range (10’) and
then attack on the next round.
Defensive Fighting: Any Character except an MU, may opt to fight defensively, bettering
their AC by 2 but sacrificing a -3 to hit. Attack rate is halved, when fighting defensively.
Disarm: Any character but a MU may attempt to disarm an opponent, who is wielding a
one-handed weapon. An attack roll is made vs. AC 2 for small weapons and AC 4 for medium
weapons, modified by the defender’s dexterity. If a hit is made, the defender must make a
saving throw to hold onto his weapon. If the save succeeds, the defender may make a free
attack against his opponent.
(the above is a slightly tweaked version of Michael Curtis' Quick & Dirty Disarm Rule.)
Mounted Attack: A mounted Fighter, Ranger or Paladin attacking enemies on foot, receives
a +1 bonus to their to hit rolls and to their AC. If attacking while riding a trained Warhorse,
or similar creature, the bonuses are at +2.
Frenzied Attack: A Fighter, Ranger, Druid or Cleric, may launch an all-out attack during a
round, putting themselves in harm’s way in an attempt to damage their opponent. They will
attack at +2 to hit, but will suffer an AC penalty of 3. A Critical Hit or Miss, made during a
Reckless Attack, might be truly awesome or utterly disastrous.
Retreat: If a creature is moving away at greater than half his normal movement rate,
opponents will get a free attack at +2 to hit and no AC adjustment from Dexterity or a shield
may be used by the defender. A character may perform a Fighting-retreat at one-third his
movement rate, but his rate of attack will be halved. This may be combined with Defensive
Fighting, with no further penalty to rate of attack.
Shield Bash: A character may forgo his shield bonus to AC and make a shield bash attack at
+1 to hit. If successful, he will do 1d4 points of damage and may make an opposed Strength
Check against his opponent, with a bonus equal to the amount of damage inflicted. If
successful, his opponent will be knocked prone. For Ogre sized creatures, the strength check
will be made with no bonus. Creatures larger than an Ogre may not be knocked prone.
Two-weapon Fighting: A character, other than an MU, with a Dexterity of 13+ may fight
using two one handed weapons, the secondary weapon being no larger than a shortsword.
This does not grant an extra attack, due to the abstract nature of combat rolls in D&D.
Fighting with two weapons grants a +1 to hit, or a -1 bonus to AC. The Player may choose
which bonus he wishes and it will be assumed to go towards his attacking abilities, if he does
not make his wishes known. The player may choose, which weapon scored the damage.