This site could be useful:
http://www.google.com

##</code><code>##

This site could be useful:
<a href="http://www.google.com">http://www.google.com</a>

##</code><code>##

@message_words = split(/ /, $message);
for($x = 0; $x < @message_words; $x++)
{
 if($message_words[$x] =~ /^http:\/\//is)
 {
  $message_words[$x] = "<a href=\"$message_words[$x]">$message_words[$x]</a>";}
 }
}
$message = join(' ', @message_words);