House Rules
Low-level or low-magic campaigns
The Normal Person: I got tired of the idea that the king's master chef also had to be able to take on half an army single-handed, so I wrote up this new set of rules for NPCs. This is for D&D 3.5.
Starting before level 1: Rules for an extraordinarily low-powered adventure.
Identifying Items Without a Spell: Alternative rules for identifying magic items.
Magic
Abstract Magic System (2E): An interesting magic system for AD&D 2R, where mages have a limited amount of magical energy with which they can try to create any effect they want.
Magical Combat (2E): An interesting idea on making mages more 'magical' in the way they fight.
The Psionics Handbook (2E): Having never seen the official Psionics Handbook, I wrote this up in 1995-96. This is for AD&D 2E.
Other rules
Mass Combat: A system of rules for mass combat, by The Sigil.
Zioth House Rules: House rules from my Zioth campaign.