A real-time feed of external links is overkill. As mentioned by others,
the chief problem is linkrot of old links. All we need to do is dump the
contents of externallinks.el_to from the database once a year or so, run
a hex to ASCII conversion on it, zip it, and email it to someone at the
Internet Archive. Anyone with access to the databases should be able to
do this fairly easily. Rather than trying to engineer a complicated
system that will take a year to implement, why not take this simple
approach that will take care of 90+% of the problem?
Ryan Kaldari