This one's also listed in the Perl Cookbook in section 15.17. Basically, you write a standard Perl script that uses Win32::Process to start your Perl.Tk program in a separate process. The original script then exits, and you're left with just your Perl/Tk app and no annoying DOS window.

Update: After posing the fair use question, and poking around on the Web, I've decided to go ahead and post the code for this. You can download it from O'Reilly, so in my mind that makes it fair game. Here it is:

#!/usr/bin/perl -w
# loader - starts Perl scripts without the annoying DOS window
use strict;
use Win32;
use Win32::Process;

# Create the process object.

Win32::Process::Create($Win32::Process::Create::ProcessObj,
    'C:/perl5/bin/perl.exe',            # Whereabouts of Perl
    'perl realprogram',                 #
    0,                                  # Don't inherit.
    DETACHED_PROCESS,                   #
    ".") or                             # current dir.
die print_error();

sub print_error() {
    return Win32::FormatMessage( Win32::GetLastError() );
}
[download]

Once again, this is from section 15.17 of the Perl Cookbook.

Guildenstern
Negaterd character class uber alles!