my @urls = ($url);
my @next_set;

while (@urls) {
    # Storage for links
    my @next_set;
    for my $url (@urls) {
        # Get the page & such
        $mechanize->get($url);
        my $page = $mechanize->content;
        my $title = $mechanize->title;
        print "<b>$title</b><br />";

        # add the pages links to the next list
        push @next_set, $mechanize->links;
    }
    # OK, we've processed all in @urls, so load @urls
    # with all the links we've found since last time,
    # and start over again.
    @urls = @next_set;
}