Increasingly, I am using bibtex entries not only with an URL field but also with an archived URL field. I have currently set these up manually.

I do not want to suggest that these become default for all users.
I want to suggest that a user could "enable" the pair of archived-url and archivel-url-access-date in the preferences and then these behave jabref-wise like any other url/access date pair fields, also allowing to open the URL easily.

A more advanced improvement might include to search for archives at the internet archive for the given URL or to create an archive with one click.