E.g. do you want keep an eye on some information which can be fetched from the net? You just write a script which regularly fetches the info and puts it into a buffer, so you can take a look at it anytime, and then regardless of platform you have that info readily available just by installing your own emacs config file.
It's much easier to write such things in emacs than curating various different scripts in various languages (python, etc.) which all require their specific support which is either available or not.