My players "dared" me to post a few of our homebrew rules expecting that I would be relentlessly flamed, but I responded by saying the boards are much more understanding and open minded; in fact, some people might actually like and/or use our homebrew rules... so here are a few ...
1) PIETY - Characters who worship the same deity as a cleric or paladin may receive an additional benefit for their devotion. Spells that are 2nd level or lower may have their durations increased from rounds to minutes and spells with durations of minutes to hours as a result of the character's piety to a specific god. Spells that have durations of instantaneous, or durations longer than one minute, or are active combat spells - such as Spiritual Weapon - are not affected by PIETY. A character may only receive the benefits of piety from one spell at a time. The caster also receives the benefit unless the target is a single target spell; unless, of course, the caster is the target of the spell. Thus, if a cleric of Desna casts Bless, then all characters who worship only Desna in the area of effect may receive the benefit of Bless for 1 hour/level of the caster instead of 1 minute/level.
2) ARCANE/DIVINE DAMAGE BONUS - Spell casters may add their spell casting attribute bonus to the damage inflicted just as a fighter adds her STR bonus to her weapon damage. The damage bonus is only added once per spell, even if the spell has multiple applications - such as Magic Missile (the first missile would receive the bonus, but none of the others from the same casting would). This bonus is only added to damaging spells, not buffing or healing spells.
3) Spellbooks can be used as "scrolls" at 1/3 the caster's level without using a spell slot, but the casting time is changed to a full round action. That is to say, a 9th level wizard could cast a 1st or 2nd level spell without using a spell slot as though she were only a 3rd level spell caster.
4) Paladins MUST be the same alignment as the god they worship and are not limited to lawful good (unless their patron god is lawful good).
5) Brew Potion - For every 5 points above the difficulty rolled to brew the potion, one additional dose of the potion is created.
I say... Have at thee! I'd be happy to post more and/or provide clarification.