for (my $i = 0; $i < @a; $i++) {
    # Do stuff with @a and @b
}

##</code><code>##

my %temp;
@temp{@a} = @b;
while (my ($a_val, $b_val) = each %temp) {
    # Do stuff with $a_val and $b_val
}

##</code><code>##

use mapcar; # This is on a node [tye] posted somewhere on PM

my @temp_arr = mapcar { \@_ } (\@a, \@b);
foreach my $vals (@temp_arr) {
    # Do stuff with $vals->[0] (from @a) and $vals->[1] (from @b)
}