The article How To Fold A Julia Fractal [1] (link via Hacker News [2]) isn't just about the Julia set [3] and their relationship to the Mandelbrot set [4], but also an explanation of imaginary numbers [5]. Even if you aren't that into math, the interactive visualizations of how imaginary numbers, Julia sets and Mandelbrot sets work is well worth checking out. This stuff almost makes sense now.
[1] http://acko.net/blog/how-to-fold-a-julia-fractal/
[2] https://news.ycombinator.com/item?id=10103083
[3] https://en.wikipedia.org/wiki/Julia_set
[4] https://en.wikipedia.org/wiki/Mandelbrot_set