Here's a list of special combat moves taken from the Conan d20 game. I've done some conversion to make them apply to normal d20 games like D&D.
I think some of them are really nice and make the game more exciting. They're not my work, so please weigh in and say what you think of them - no-one here is going to be offended (normal posting rules apply, or the Mods will get you!) - are they too powerful, are they too dificult to qualify for, are they too complex..?
Thanks!

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Bull’s Charge
A low charge can get you under your enemy’s guard to stab deep into his belly. However, doing so renders you very vulnerable to a counterattack.

Cat’s Parry
You parry your opponent’s wrist, rather than his blade.
Dance Aside
You shift out of the reach of incompetent opponents.
Decapitating Slash
You take advantage of an opponent’s dropped defences to slice his head clean off. This leaves you open to counterattack and so is usually only done if you are only fighting one opponent.
Devastating Sweep
You can swing your weapon around, forcing your foes back to clear sufficient space for you to flee.
Fling Aside
If you are sufficiently strong, you can simply pick up your enemy one-handed and hurl him aside.
Force Back
Your powerful attack forces an opponent to move 5ft back or take extra damage.
Human Shield
You swing your distracted enemy around so as to attempt to parry another enemy’s attack with the body.
Leaping Charge
You recklessly leap in to combat.
Leave Them for Dead
You ignore lesser foes, trusting your attack to finish them.
Pantherish Twist
When two attackers attempt to flank you, you twist away at the last moment, forcing them to attack one another.
Ranged Disarm
Taking careful aim, you shoot the weapon out of your enemy's hand.
Retreating Shot
Dodging out of reach, you take a shot as you retreat.
Riposte
When fighting defensively, you parry skillfully enough to open up your opponent’s defence.
Sniper's Sneak Attack
You can take advantage of your target's obliviousness even at long ranges.
Sundering Parry
Rather than simply setting aside your opponent’s weapon, you attempt to hack it through with your own.
Swap Places
Your coordinate with your ally to switch positions in combat.
To the Hilt
You take advantage of your enemy’s lack of armour to plunge your weapon deeper into his body, leaving it amidst his flesh.

Overall, they're not bad - the prerequisites are reasonable, and there's always a reason to NOT perform one of these manouevres, as well as a reason why you might want to.

The only exception is Desperate Stab. Suddenly every melee fighter (of sufficient level) carries 3-4 levels of rogue in it, so that they can add 2d6 to the fort save required - the same things that allow Desperate Stab also allow Sneak Attacks. Spell-storing weapons will be similarly open to abuse.

I think I agree - I've never been comfortable with save-or-die effects, and this one is open to abuse. To be Devil's Advocate, though... You have to have a Base Attack Bonus of +15 to do this. That makes you at least 15th level, possibly higher. The opponents you're facing at this level should be able to shrug off Fort saves reasonably well - a 15th level wizard gets +5 to Fort saves, plus their protective items. On the subject of protective items, the opponent is relatively likely to be immune to death effects by now, too...

But yes. A Blackguard, without taking any BAB-sapping levels of rogue, can have +3d6 sneak attack damage. +4d6 at 15th level if they were a 5th or higher level paladin before they turned Blackguard... You want one of those guys hitting you with a spiked chain (a finessable weapon) for 2d4+7 (+ power attack) +4d6 and having to beat the damage as a Fort save?
(That averages 28 before adding power attack, which would be doubled for being a two-handed weapon, of course... and maybe Smite Good, which would be +10 more, cause they're so evil.)

I've edited out the Desparate Stab move - it is too awesome and open to abuse.

Below is a list of the moves, in the order of the feats required to qualify for them.

Essentially, these moves act as extension to the feats that form part of their prerequisites. In this system, for example, if you have the Dodge feat, not only can you assign a +1 defense against a particular foe, but you get to Dance Aside if anyone attacking you misses by half or more of your total defence.

Currently, Dodge and Power Attack have the most moves associated with them. Perhaps we'll add more later, but that's what the Conan game, where these come from, focuses on - awesome melee combat.

No feat required

Decapitating Slash
You take advantage of an opponent’s dropped defences to slice his head clean off. This leaves you open to counterattack and so is usually only done if you are only fighting one opponent.


Leaping Charge
You recklessly leap in to combat.


Swap Places
Your coordinate with your ally to switch positions in combat.


Dodge

Dance Aside
You shift out of the reach of incompetent opponents.


Devastating Sweep
You can swing your weapon around, forcing your foes back to clear sufficient space for you to flee.


Pantherish Twist
When two attackers attempt to flank you, you twist away at the last moment, forcing them to attack one another.


Combat Expertise

Cat’s Parry
You parry your opponent’s wrist, rather than his blade.


Devastating Sweep
You can swing your weapon around, forcing your foes back to clear sufficient space for you to flee.
See above.

Riposte
When fighting defensively, you parry skillfully enough to open up your opponent’s defence.


Power Attack

Bull’s Charge
A low charge can get you under your enemy’s guard to stab deep into his belly. However, doing so renders you very vulnerable to a counterattack.


Force Back
Your powerful attack forces an opponent to move 5ft back or take extra damage.


Leave Them for Dead
You ignore lesser foes, trusting your attack to finish them.


Sundering Parry
Rather than simply setting aside your opponent’s weapon, you attempt to hack it through with your own.


To the Hilt
You take advantage of your enemy’s lack of armour to plunge your weapon deeper into his body, leaving it amidst his flesh.


Improved Grapple

Fling Aside
If you are sufficiently strong, you can simply pick up your enemy one-handed and hurl him aside.


Human Shield
You swing your distracted enemy around so as to attempt to parry another enemy’s attack with the body.

Added "Swap Places" and tidied up the formatting.

I propose we adopt these in D&D next session. Generally, that'll only mean we'll see Bull's Charge, Dance Aside, Swap Places, and maybe Cat's Parry, Force Back and a few others.

Couple of proposals to add something for people who prefer ranged combat:

Retreating Shot
Dodging out of reach, you take a shot as you retreat.
Prerequisite: Point Blank Shot, BAB +4
Effect: As a full round action, you move up to your movement rate away from threatening melee opponent and take a ranged attack against him. You gain a +4 dodge bonus to AC with respect to the Attacks of Opportunity caused when moving away from that foe.

Ranged Disarm
Taking careful aim, you shoot the weapon out of your enemy's hand.
Prerequisite: Point Blank Shot, Precise Shot, BAB +4
Effect: As a standard action, you and the defender make opposed attack rolls. You take a -4 penalty, the defender takes the normal penalties and bonuses of the Disarm move. If you win, roll half damage against the defender. If the result is 1 or more after any damage reduction, the defender has dropped their weapon to the floor in their space.

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Do these seem reasonably balanced?

These both seem fair. I especially like the sound of the second one!

Here's another one.

Sniper's Sneak Attack
You can take advantage of your target's obliviousness even at long ranges.
Prerequisite: Point Blank Shot, Far Shot, Sneak Attack
Effect: As a full round action, you carefully aim on a target who meets the criterea for Sneak Attack, regardless of range. If your attack hits, you may apply your Sneak Attack damage.
Normal: Usually, you may only Sneak Attack targets within 30 feet.

Added the ranged moves into the main post.

Ranged Disarm
Taking careful aim, you shoot the weapon out of your enemy's hand.

Retreating Shot
Dodging out of reach, you take a shot as you retreat.

Sniper's Sneak Attack
You can take advantage of your target's obliviousness even at long ranges.