These are all apps that I primarily wrote for myself because I wanted a program that did something very specific and I couldn't find such a program, or because I didn't want to trust some random developer by running their program on my computer.

iTunesPlaylistExport Export iTunes® playlists to WPL, M3U, or M3U8 format with a command line interface
  folderClone clone one folder to another. Faster than robocopy®, doesn't break after service pack updates like xxcopy™
  cEcho Command shell utility that replaces the Echo command and allows for different colors