I have played many roleplaying games over the years. Such as GURPS and World of Darkness but my all time favorite has always been WFRP. I have been playing 3rd edition since December and today I've come up with a awesome house rule that takes some of my knowledge of other cool systems and puts it back into warhammer. I've decided to make a flaw/disadvantages system (since the Old World is filled with flawed people and adventurers are no exception).
I didn't want to make it easy to min/max with this house rule so I have set a few limits on flaws. First of all each character can only ever have one flaw (since one awesome weakness is better then 10 minor ones). I have decided that flaws are kind of like anti-specialisations that give misfortune dice in a certain situation but give you a free pre-set specialisation in return. Here is a sample list of flaws I came up with:
Superstitious : You are very superstitious and will believe a witch or spell is behind everything. Even strange weather or black cat crossing your path is an omen or portent. Though most peasants in the Old World tend to think this way but you are a really extreme case. Spell casters gain a fortune dice when casting a spell on you but you gain the Folklore (urban legends) specialisation.
Wild man/Wild woman : You are at home in the forests and natural places of the Old World. You can find your way through these wild places with ease and might even a bunch of small animals that follow you around (though most people will think this is creepy). You gain a misfortune dice when making charm rolls with city folk (villages that are close to the woods usually don't count) but gain the Nature Lore (Navigation) specialisation.
Obsessed with death : You know you are going to die some day. You know you will die soon. You live every day as if it is your last but act grimly around others. Some more foolish optimistic people don't think about the moment of their death so they will not see it coming but you know better... You gain a misfortune dice on resilience rolls to naturally heal wounds through resting but due to your grim nature you gain the Charm (Priest of Morr) specialisation.
More flaws to come but you can post other ideas for new flaws or alter the ones I have created as you see fit as well as suggest tweaks to overall flaw system.