I assume you're referring to an extension that would allow embedding or showing extracts to any kind of linked file?
If the file is hosted on a well known service, for example on Pastebin or GitHub Gist, the MediaEmbed feature of TextFormatter, which can be enabled by the FoF Formatting extension might be what you need. Which files can be embedded will depend on each of the third-party services. For example I think you can also embed from Google Drive with that extension.
If you're looking for a general purpose extension that would render links that point anywhere, I don't think there's any such extension that exists at this time.
If you're looking at developing it, you could take inspiration from the AutoURL, AutoImage, and AutoVideo features that are present in TextFormatter.
You will need to use a library or another third-party service to render some sort of reader for each kind of file you want to support. There will likely also be security considerations since you might not want to have the visitor's browser automatically download the files (and it might not be possible at all due to cross-domain) so you will also need some kind of cache/proxy feature.
