Actually, with the most recent Tk releases 804.* it is possible to configure the following options independantly for each list item: background, foreground, selectbackground, and selectforeground.

So long as you were using one of the newer releases, you could do something like this:

use Tk;

my $mw = MainWindow->new;
my @colors = qw(red orange yellow green blue purple);

my $listbox = $mw->Listbox(
   -height => 0,
   -foreground => 'white'
)->pack;

foreach my $c (@colors) 
{
   $listbox->insert('end', $c);
   $listbox->itemconfigure('end', -background => $c);
}

MainLoop;
[download]

As mentioned previously, HList can also support this functionality... and more besides. The tradeoff is that it's slightly more complex to configure.

Tk::TextList will also provide this functionality, and more

As a side note: It appears that there is a memory leak with Tk::Listbox in the most recent releases, so take that into consideration.

Rob