Another example is that complicated systems often get to the point where a great deal of their functionality becomes highly configurable. Where they are essentially either creating their own scripting language (less common today, but this was much more common a decade ago), or reading a great deal of data to determine their runtime configuration. Taken to an extreme, you get to where the lines between data and code start to become blurred. When the code being executed at runtime is really a series of functions that are dynamically strung together, you're starting to make a list-like system, arguably.
