The Complete Book of Skills and Supplemental Non-Combat Options (2010)

From Introduction:

The combat mechanics of 4th edition are some of the most detailed, rich, and involved combat systems that have ever been published in a fantasy role-playing game. It is easy and intuitive, yet as tactical as the players and the DM want it to be. What seems to have taken a back seat in 4th edition, however, are the skills. The skill list for 4th edition is a fully-functioning one, but many have expressed a desire for more depth and more choices when it comes to what their characters know outside of combat. The default skills can function in a full capacity, but there is a high degree of abstraction that is necessary to make this possible. What this guide hopes to accomplish is to restore some of the specifics to the skill system from editions past.