Well written article critically examining the 3.5 diplomacy skill, and building a replacement mechanic in a sensible way.
This is a great way to approach making changes to a game's mechanics.
Borderlands 2 skill calculator I made.
Skill calculator I made for Borderlands 2. This is Maya's skill tree.
Skill calculator I made for Borderlands 2. This is Zer0's skill tree.
Skill calculator I made for Borderlands 2. This is Axton's skill tree.
Skill calculator I made for Borderlands 2. This is Salvador's skill tree.