"The Skill Challenges of War" was quite easily the longest running series here at The Core Mechanic, the second longest was my 5-part series "The New Cleric is the Old Cleric". I couldn't have done it without the help of my two comrades in blogging: Gamefiend from At-Will, and Madbrew from Mad Brew Labs. 14 Parts altogether! Also, there should be a 15th post soon that will present the whole series together as a single PDF for you to download and print out without all the adverts, etc.
Here I provide you with all the links to each of the other posts in the series.