For me, a good personal project usually evolves from some sort of process I've already been doing or thinking about, sometimes for several years. At some point in time, the weight (or burden?) of the process and the resulting intense familiarity with the subject matter sparks a need to better understand it or appreciate it through visualization and/or analysis. As an obvious side effect, personal projects also help me learn new tricks as well as sharpen my existing skillset. Here's a look at a few of my favorites, which live at my personal site joshfallon.com.