I used to have quite a few house rules in my game. Over time I've cut them back where I found they were becoming rules just for the sake of extra rules, rather than adding to the game. Here are a few of the house rules
1. No spiked chains or floaty shields. They do not exist in my game.
My experience with spiked chains in my game has been that they are too powerful. I think floaty shields are borderline, plus I really don't like the concept of them either (yes, I realise the irony of this in a game where PC's fight giant eyes that fire rays at you and shoot balls of fire from their hands).
2. Rogues are automatically entitled to a Search check to find traps when moving carefully (half-speed) and passing within 5 feet of a trap. This ability works like the Elven ability to find secret doors.
I found this rule stops the continuous "I'm searching for traps" that can sometimes occur.
3. To increase ranks in a skill that you already have ranks in, or in a skill that you can use untrained, you must have used the skill during your previous level. This may have been during the adventure or in the down time between adventures. If it was during the down time during adventures provide a short explanation as to how you used the skill.
I just think it adds a little bit of realism to the game (once again I realise the irony of this statement, but I don't care!

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4. Characters die at -10 minus their constitution modifier (instead of -10).
5. Failing a massive damage save drops you to -1 hit point (instead of immediately killing you).
Both of these rules help reduce character death a little, without putting the baby gloves on too much. Plus the massive damage saves start becoming commonplace at higher levels.
6. On a threat, a 20 on the critical confirmation roll adds an extra multiple to the damage and you roll again, adding an extra multiple every time you roll another 20 (i.e. a 20 on a critical confirmation roll increases a x2 critical to a x3 critical).
I don't like the auto-kill on a triple 20 roll, but I do think that confirming on a 20 should be worth a little more. The best I think we got was a x3 weapon that got increased to x4 after a 20 on a confirmation roll.
7. Characters receive 3 action points per level. They can be used as per the rules in Unearthed Arcana. Points do not carry over from one level to the next. When you level up all unused action points are lost.
I like the action points rules, but I found that the players ended up with too many. Capping them at 3 max means that they are still there to use, but are limited.
They normally get used to increase save rolls where a player has rolled low, or to emulate the Improved Toughness feat to give a PC more hit points to save him from death. It only lasts for 1 round, but that is usually enough time for the Cleric to get over and save his buddy.
It has meant there have been less deaths in my game, but I'm fine with that as myself and the players play long ongoing campaigns and generally don't change PC's. It allows me to not hold back with my punches for the bad guys as I know that there is a little bit of a safety net there.
It doesn't mean that there are no deaths in my game, but it has stopped a few.
Olaf the Stout