dhoss,
Actually, I just realized you could have a monster on your hands without one more sanity check:

# push @work, get_links($link);
push @work, get_links($link) if ! off_site($link);
[download]

I am sure somewhere on the university website there is a link off-site and you don't want to end up crawling the entire internet - it could take a while (and get you fired).