my %people = ( 7 => { name    => 'Bob Jones',
                      address => '555 Anywhere Street',
                      city    => 'Allentown',
                      state   => 'Pennsylvania' },
               3 => { name    => 'Pete Hollister',
                      address => '222 Northview Drive',
                      city    => 'Shoreham',
                      state   => 'unknown' },
               9 => { name    => 'Pete Hollister',
                      address => '222 Northview Drive',
                      city    => 'New York',
                      state   => 'unknown' }
              );

my $name = 'Pete Hollister';

my @cities = map { $people{ $_ }{ name } eq $name ? $people{ $_ }{ city } : () } keys %people;

$,=', '; # This sets the array separator to a comma and space, allowing
         # easy printing of arrays
print @cities;