My house rules involve both crunch and fluff, and some of them are due to us using a homebrew world rather than Howard's. So here's the chant:
Skills are consolidated as follows:
Acrobatics DEX (Balance, Tumble)
Athletics STR (Climb, Jump, Swim)
Stealth DEX (Hide, Move Silently)
Perception WIS (Listen, Spot)
Gear
Some items have been culled entirely, mainly arbalest, crossbow and plate armour because they don't fit in the setting. Others can only be found as relics. Some other items (weapon, armour) have been changed stat-wise.
Most importantly, two-handed weapons damage has been reduced (typically by 1 step, so 2d10 becomes 2d8 and so forth).
Prices have been revised, a typical silber piece weighs about 2 grams, and gold is worth 20 times its weight in silver. (This is mainly to avoid lugging around a half ton of cash)
Combat
* 5' Step does not draw an AoO
* Power Attack: no double damage bonus for two-handed attacks
* Two-Weapon Strike (Hyboria's Fiercest) is a combat manoeuvre, not a feat, and does not have Power Attack as prereq
* Sunder attempts can damage both weapons involved
* Ranged Finesse: _every_ Ranged Attack is handled as Finesse attack, i.e. if the attack roll exceeds DV+DR, DR is completely ignored.
* Massive Damage reduces you to -1HP and dying (not -10, dead)