My four Universal House Rules:
UHR #1: Skill and Feat Revisions: This UHR is sort of a "cheat" on my part, as it incorporates several house rules in one, simply because they are based on a common theme and all work together with one another. Most notable highlights are an upgraded form of Toughness, a few new feats to make Dex-based fighters more versatile (e.g. the Called Shot feat which is the Dex-based version of Power Attack), and a major revision to how spending skill points works for Craft, Knowledge, and Perform. I do like Rich Burlew's Diplomacy rules EXCEPTING the idea that a 20th-level ally will NEVER pass the salt at the dinner table unless you are a high-level bard and have prepared a love poem rivaling the works of Shakespeare.
UHR #2: Point-based Ability Increase By Level: With this UHR, a character gets points to increase their abiity scores as per the point buy rules, at a fixed rate. All characters start with 25 effective points and get a certain amount at each level increase, so characters with weak stats will get a quick boost at 2nd-level and characters with exceptionally high stats may not get to spend any points for several levels. I do grant at least the standard +1 to one ability score every 4 levels for those with high ability scores, though most of my score generation since I adopted this variant favors "standard" die rolls in the 4d6, drop lowest, arrange as desired format. Regardless of how many points a character picks up at any given level, any one ability score can only increase by 1 per level.
UHR #3: Feat Every Level: As explained by Crothian. This applies to PCs, NPCs, and creatures that get feats based on HD (so, animals don't get a feat every level because they never get them in the first place, but dragons do and let me tell you a dragon with 44 feats is scary). It doesn't overpower PCs to the point of breaking the game, and it allows monsters to get some abilities they should have been given in the first place (anything really big should be able to Crush opponents with ease, without having to sacrifice one of a paltry three monster feats for the monster I'm thinking of as I write).
UHR #4: Variant Multiclass Rules Complex and difficult to explain. If you want a basic outline, go read
this thread.
So far the first three have worked great. All my current games use the Gestalt rules, so I've yet to test and tweak #4. There's always next campaign...
Oh, and as for why... "Oh, it's complicated." - Fernand Mondego,
The Count of Monte Cristo (movie)