Windows doesn't have a command line utility for compressing files (that I know of), and I had to come up with a way to automate some file transfers today. So I whipped up a tiny Perl script that will zip up a file. I figure someone else might need it. (Or someone might know how to do this in one line.) You'll need the Archive::Zip module, and the following code—which is pretty much right out of the documentation:

# Grab the incoming file
my $argv = join(' ', @ARGV) or die "Usage: zipme.pl [file location]\n";

# Grab the file name
my($dir, $file) = $argv =~ m/(.*\\)(.*)$/;

# Create a Zip file
use Archive::Zip qw( :ERROR_CODES :CONSTANTS );
my $zip = Archive::Zip->new();

# Add the file
my $file_member = $zip->addFile($argv, $file);

# Save the Zip file
unless ( $zip->writeToFileNamed($argv.'.zip') == AZ_OK ) {
    die 'couldn\'t zip';
}

Save this code as zipme.pl, and you'll be set. Pass in a filename, and you'll get a compressed file of the same name plus the .zip extension. So:

C:\>perl zipme.pl C:\path\to\giant.file

will give you C:\path\to\giant.file.zip. It works well with Windows batch files, and will save me a bunch of bandwidth.