Regex implementation. Has matching groups and backreferences. These features are not possible with a typical simple DFA implementation.
Simple sentence generator. Reads text from file, and generates similar-ish text. Can sometimes give humorous sentences.
Computes distribution of hands (straight flush etc).
Handwritten json parser. Builds tree representation of json.
Function that computes derivatives of functions. Produces a plot of original function and deriv, printed to stdout. Zoom out terminal to get a good plot.
Takes two strings A and B and returns a "patch" that can transform A into B.
Postifx notation calculator. Example: 2 2 + 2 * == 8
Somewhat of a du replacement. Outputs how much disk usage is occupied by a given depth of subdirectories