A bit longer than BrowserUK's approach, but probably easier to understand and a bit more robust:

#!/usr/bin/perl

use strict;

my $list = '1-5,6a-e,7,10-13';

my @list = split(/\s*,\s*/, $list);
print join("\n", expand($_)), "\n" foreach @list;

sub expand {
    my $str = shift;
    if ($str =~ /^(\d+)\-(\d+)$/) {
        return ($1..$2);
    } elsif ($str =~ /^(\d+)([a-z]+)\-([a-z]+)$/) {
        return map {$1.$_} ($2..$3);
    } elsif ($str =~ /^\d+$/) {
        return $str;
    } else {f
        die("wrong format");
    }
}
[download]

Note that it doesn't check whether the ranges are valid, e.g. whether $1 <= $2, but that's trivial to add.

Hope this helps, -gjb-