UnarmedCombatMethods - a new take on unarmed combat, utilizing the existing weapon system's ideas of handedness (Light, One-handed, or Two-handed) and complexity (Simple, Martial, or Exotic) to create a rich but easy-to-use unarmed combat system.
AbstractArmor - This rule aims to replace the standard armor table with a more abstract treatment. Do you want a feather-light chainmail? What about dragon-leather? Materials are cosmetic in this rule. (Note - this is an IH houserule with a trivial provided conversion for use in a standard d20 game.)
Turning - The standard turning rules are a piece of crap. They're clunky, use radically different mechanics than anything else in the game, and become nearly unusable at higher levels against CR-appropriate foes. While there are many complete overhauls to the turning system, this houserule merely changes the mechanics to use a simpler, streamlined mechanic that meshes well with the effects of ordinary combat.
ChakraBinding - Want a low-wealth game without radically rebalancing combat or switching to Iron Heroes? With Chakra Binding you can have characters that are still decked out with magical effects without simultaneously giving them the ability to buy mid-sized countries.
Diplomacy - Diplomacy sucks. We all know this. This rewrite of the skill makes it stop sucking.
CombatModes - I feel that the disconnect between the way natural and manufactured weapons work is unacceptable. It creates both confusion and contradiction. This is my attempt to combine the rules in a way that changes absolutely nothing in 95% of cases.
ExertionLevels - This is a generalization of the exertion levels implied in walking/hustling/running, so that you can easily use these rules elsewhere.
WeaponConstruction - Want to wield a club *and* use a high-crit weapon, but frustrated by the lack of such things on the weapon list? Not quite sure if the new weapon you created is balanced with the given stats? These rules allow you to build weapon stats from scratch, thus decoupling flavor from mechanics.
Language - I've never been satisfied with Speak Language. It's a kludge, rammed into the existing skill system. While I've seen some good improvements to it, this is a complete rewrite, making it into a proper skill while maintaining the ease-of-use that it currently has.
ToolsAndLibraries - A unification and extension of the rules concerning tools, making it easy to craft tools for any skill. As well, a simple rule for determining how good a library is, and how easy it is to use.
PowerAttack - PA is a bit broken. It's never advantageous to PA for more than a couple of points unless you have a massive advantage somehow, in which you're exploiting the system. As well, it gets worse and worse at higher levels as average damage rises. This fixes both of those problems at once.
SkillRanks - I've been unhappy with the results of D&D's skill system. This is a tweak to simplify and strengthen it. No major changes to DCs or uses or anything, just a change in how skill levels are determined and handled.
DeathAndDying - You're playing a game, not watching a historical sim. This is heroic realism we're talking about here. Since when did a heroic character die from a crit without accomplishing something important first?