Vim. I felt like I was slowly going crazy due to the friction between my thoughts and the commands needed to navigate through the code. I was just looking for a tool to solve that and happened upon an article about Vim. A teacher had tried to show me Vim in high school, but I slowly backed away from his crazed stare. But now, I came to it of my own volition. It's great. It feels like the one tool which allows me to freely express what I want without getting in the way. Add to this a suite of simple yet powerful tools, such as recursive macros, which mean I can usually automate tedious and repetitive tasks.