The house rule that had the most impact for us is a simplified initiative system. The phases are gone, and it's just initiative rolls to determine order of PC actions. Who's to say the Mage is a little slower or was just too focused on casting the spell that the Burglar gets to take a swing at him with his short sword? Or the Archer was trying to get the shot lined up and someone bowls into him knocking him aside? Maybe the Archer does loose the arrow before the fighter takes a swing. Maybe they go off at the same time.
I can see the rationale behind the phases and why ease phase happens and for what reason, but when GMing a group of 5+ players, the ease of simplified Initiative works well for us.
One house rule we did adopt since we start all of our PCs at level 5, is that after Adolescent level 0 or Level 1, all the Temporary Stats reach the Potential stats, and the players get their full DP's for the remaining levels of skill purchases. The rationale being this: The adventuring world is dangerous and difficult, that's why everyone isn't an adventurer. Something sets you apart and makes you keen for the adventuring life. You developed more rapidly than the "average" being, you reached your potential much sooner than the "average" being. You are more suited to the adventuring life than that of your neighbor or parents or friends or the town mayor.
Remember: You are unique... just like everyone else.