House Rule: The "Good-At" System

More relevant to this post than I originally intended!

In trying to define the human cultures of my game world (the only race that will be present in my campaign is human, but with various cultures), I am modeling them after different real-world cultures I find interesting, or a mix of real-world cultures that I think creates a fun role to play.  However, I was faced with the fact that my players are number-crunching, game-busting, min/max-happy power gamers who are going to have to get used to old-school RPGs again.  Some of them have never played anything older than 3rd Edition, and most haven't played anything other than 3rd or 4th Edition for over 10 years.  I'm certain they'll be sold on it once we get underway, but I wanted a bonus to dangle under their noses to make their choice of a human culture "mechanically" different as well as a different shade of fluff.  

So, I came up with the "good-at" system.  What is it?  Just what it says.  A character of the nationality in question is "good at" something that is needed in his society, giving him a +1 or +5% on any D20 or D100 roll required in relation to a task that is relevant to his "good-at" ability.  There might be a few choices for some cultures.  For example, Ingurista is a coastal nation that is modeled after medieval Spain in quite a few ways.  Fishing is their main occupation and fish are responsible for the livelihood of many of their citizens.  A player with an Inguristan character could choose to be "good at" sailing on a boat.  He would receive a +1 or +5% to any D20 roll or D100 roll relating to sailing a ship.  Think of it as Secondary Skills from AD&D without the random roll or subsystem to determine what skill you get.  A player with a Horseclanner character, modeled on a mix of Mongolian and Native American culture, who live on the cold Deathwind Steppe, might choose a "good-at" ability of surviving in the cold, granting a +1 or +5% to any roll relating to surviving in cold weather.  It would certainly apply in foraging situations, building a shelter, etc.

If you have any ideas after you read this, feel free to comment.  It's a system that works for me and is very simple and open to interpretation, which is what the OSR is all about to me. 

Keep on playing!