When I was in college, I wrote a program just for fun to generate Perlin noise textures. Perlin noise is technique used to create natural-looking textures — clouds, for example.
Later, for a technical writing course, I created a more user-friendly interface for that program and a web page where people could download the program, along with the source code. That page was the most popular part of my website — it was the first Google result for "perlin noise generator" at the time.
I also posted the source code for my program on that page. I eventually learned that my implementation of Perlin noise wasn't truly Perlin noise after all, but rather a simplified version. I hadn't realized that at the time because I hadn't taken enough math courses yet to fully understand Ken Perlin's original papers. I took down that site long ago, partly because I was embarrassed about having propagated that mistake. But strangely enough, you can still find copies of that source code on the web by searching for some of the variable names.
Anyway, true Perlin noise or not, I thought it might be fun to re-write that UI in XAML and submit it to the Windows app store. The version I submitted is about the same as my original version, except with a prettier, touch-friendly UI. Someday, I'd like to add more features and make it more of an educational tool to let people see visually how the noise is generated. But for now, it's fun to play with and can generate some pretty cool images.