while (1) {
    while (<INPUT>) { .... }
    sleep $delay_period;
    seek(INPUT, 0, 1);
}

##</code><code>##

#!/usr/bin/perl -w

use CGI; 
use strict;

my $query = new CGI; 

print $query->header(), 
   $query->start_html(-title=>"My log file"), 
   $query->h1('Tail');
# put your tailing method here
while (1) {
    while (my $input = <INPUT>) {join('',$input,'<br/>'); print $input;}
    sleep $delay_period;
    seek(INPUT, 0, 1);
}
print $query->end_html();