#The || ''; part is not needed; could be my $monk2 = shift;
my $monk2 = shift || '';

#The $xml && $xml =~ ... is not needed.  Also, the regex can
#be simplified a bit.  How about this:
#           if($xml =~ m|^(?:ht|f)tp://|) { ...
if ($xml && $xml =~ /^(http:\/\/|ftp:\/\/)/) {
...
#Just a small thing; if efficiency is a concern you may wish
#to try this regex: /^([Ee]|[Mm][Ii])/; /i has some overhead
$units = ($units =~ /^(e|mi)/i)? 'mi.': 'km';
...