One of my team members managed to find a confusing sounding, but actually excellent solution, to this problem. Jesse Middleton posted this last year, and while some minor things have changed, it still works very well. Thanks Jesse! The basic steps are as follows:
- Register yourself with the Google Apps marketplace as a vendor.
- Create an application (with the sole purpose being to put a link on the menu bar).
- Add the application to your domain.
Because you're not actually publishing your app to the Google Apps Marketplace, it doesn't cost anything to do this, and won't get in anyone's way. You can create as many apps as you might want, for links to various things. Some enterprising individual should take this method and expand on it to allow people to rename and customise these menu items at will.