I know this topic has been coming up lately, at first I thought it would be ridiculously overpowered, but I think it can become a balanced feat. Here's my attempt.
Big Guy/Gal [Feat]
Prerequisites: Medium-sized Humanoid or Outsider, 1st level
Benefit: You are taller than average (at least 8 ft.) and you can learn to use this to your advantage. You are considered to be Large, and threaten foes with a 10' reach. As a large humanoid (or outsider) you suffer a -1 to AC and a -1 to hit and a -4 to Hide checks. Any armor that would normally fit a medium-size member of your race can be refitted to you for twice the cost. You must take an additional feat to use Large weapons in 1 hand or Huge weapons.
Special: Spells or effects that only affect Medium or Small creatures still affect you, despite your size (ie- Charm Person).
Large Weapon Proficiency [Feat]
Prerequisites: Large Sized
Benefit: If you do not already have proficiency with Huge sized weapons, this feat grants proficiency. Additionally you can now use Large weapons in a single hand without penalty. You do not gain any additional weapon proficiencies, so if you were only proficient with Simple weapons you can now use Lareg Simple weapons in 1 hand or Huge Simple weapons in 2 hands.
Small Guy/Gal [Feat]
Prerequisites: Medium-sized Humanoid or Outsider, 1st level
Benefit: Your are smaller than average (at most 4ft. tall). You are considered to be Small and your base movement is 20 ft. As a small humanoid (or outsider) you gain a +1 to hit and a +1 to AC, and a +4 to hide checks. You must use armor appropriate to your size (as gnomes and halflings) and you must wield a medium-size weapon in 2-hands.
Special: Small guys/gals are known and universally ridiculed and stereotyped as munchkins. You must get approval from your dm to use this feat!
Technik
Big Guy/Gal [Feat]
Prerequisites: Medium-sized Humanoid or Outsider, 1st level
Benefit: You are taller than average (at least 8 ft.) and you can learn to use this to your advantage. You are considered to be Large, and threaten foes with a 10' reach. As a large humanoid (or outsider) you suffer a -1 to AC and a -1 to hit and a -4 to Hide checks. Any armor that would normally fit a medium-size member of your race can be refitted to you for twice the cost. You must take an additional feat to use Large weapons in 1 hand or Huge weapons.
Special: Spells or effects that only affect Medium or Small creatures still affect you, despite your size (ie- Charm Person).
Large Weapon Proficiency [Feat]
Prerequisites: Large Sized
Benefit: If you do not already have proficiency with Huge sized weapons, this feat grants proficiency. Additionally you can now use Large weapons in a single hand without penalty. You do not gain any additional weapon proficiencies, so if you were only proficient with Simple weapons you can now use Lareg Simple weapons in 1 hand or Huge Simple weapons in 2 hands.
Small Guy/Gal [Feat]
Prerequisites: Medium-sized Humanoid or Outsider, 1st level
Benefit: Your are smaller than average (at most 4ft. tall). You are considered to be Small and your base movement is 20 ft. As a small humanoid (or outsider) you gain a +1 to hit and a +1 to AC, and a +4 to hide checks. You must use armor appropriate to your size (as gnomes and halflings) and you must wield a medium-size weapon in 2-hands.
Special: Small guys/gals are known and universally ridiculed and stereotyped as munchkins. You must get approval from your dm to use this feat!

Technik