Hotshot, others have explained why using symbolic references is a bad idea, here's an alternative:

my %hash_of_arrays;

$tmp =~ /(.+)(\d+)$/;
$hash_of_arrays{$1}->[$2] = $the_thing_to_store ;

use Data::Dumper; print Dumper(\%hash_of_arrays);
[download]

hth, andy.

Update: dammit, davorg's already said that! I plead snow blindness.