Back in an old Skyrim thread, I proposed the following idea for armor:
1.) No "armor classes" (light, medium, heavy, etc.) You can wear any type of armor in any combination. The "class" of armor you're wearing is dictated by the overall weight, not the type. So a full set of plate armor would count as "heavy" armor. Swapping out the gauntlets and greaves for leather gloves and boots, ditching your helm, and removing one pauldron could lower the weight enough for it to be "medium" armor.
2.) Skills would be exclusive to certain armor weights. "Heavy" allows access only to power attacks and ripostes, low stealth, slow magic. "Medium" adds finesse attacks and longer combos, moderate stealth, moderate casting times. "Light" includes all of that plus acrobatics and leaping attacks, good stealth, faster casting times. This way, actual interactive gameplay changes based on the armor class, instead of just a few behind-the-scenes checks.
The above would allow for a huge number of weapon / armor / clothing combos and create really interesting looks. Players would no longer be limited to selecting from only a few armor sets to maximize your character. The whole range of game armors would be available to every character to mix-and-match; we would simply need to ensure our weight did not exceed the threshold for our desired armor class.