Dependency only RPM

[Andy Armstrong]

I'm trying to make an RPM that does nothing apart from require a bunch of other packages. Google hasn't enlightened me so far. I tried a spec file with a few Requires like this:

Summary: My App
Name: my-app
Version: 0.0.1
Release: 1
#Source0: %{name}-%{version}.tar.gz
Vendor: My Corporation
License: GPL
Requires: httpd >= 2.2.3
Requires: java-1.6.0-openjdk >= 1.6.0.0
Requires: java-1.6.0-openjdk-devel >= 1.6.0.0
Requires: postfix >= 2.3.3
Requires: postgresql >= 8.1
Requires: postgresql-jdbc >= 8.1
Requires: postgresql-server >= 8.1
BuildArch: noarch 
%description
My Application

rpmbuild -bs myapp.spec builds an SRPM successfully - but I assume I need to build a binary RPM and rpmbuild -bb doesn't produce anything.

Is it possible to build a dependency-only RPM?

Thanks.

-- 
Andy Armstrong, Hexten