Special issue dedicated to the history, philosophy and meaning of category theory. The articles in this issue are freely available. Not sure if they'll be that way for long, or what.
Table of Contents:I've always been interested in the Philosophia Mathematica journal because it is edited by (and, IIRC, was also founded by) one of my first year calculus professors at the University of Manitoba. It's a journal that discusses mathematics in a philosophical sense (hence the name). So, instead of technically oriented articles, you have articles that look at mathematics and ask "why" at the meta-level.
Categories in Context: Historical, Foundational, and Philosophical
Learning from Questions on Categorical Foundations
Categories, Structures, and the Frege-Hilbert Controversy: The Status of Meta-mathematics