Letting users select timezone

Hi,
  I've been working on a membership system, letting users select their 
timezone when the signup.

I'm a bit confused as how to generate the timezone selection box. I've 
tried the routines:-

    use DateTime::TimeZone;
    my @array = DateTime::TimeZone->all_names;
    print "@array\n\n";
    @array = DateTime::TimeZone->categories;
    print "@array\n\n";
    my %hash = DateTime::TimeZone->links;
    foreach my $key (keys %hash) {
        print "$key = $hash{$key}\n";
    }#foreach

But 'all_names' and 'links' both return a lot of options, 'categories' 
doesn't return enough.

Is there something similar to the time zone selection you get in Windows 
or similar programs? The GMT, GMT+1, etc...

Right now I think I must be missing something and I can't see how to get 
what I need...

Help much appreciated.


Lyle