As I’ve been testing out Gmail for my domain, I read in “Google Apps: The Missing Manual” that the Google Toolbar had all kinds of nice buttons that integrated nicely with Google Apps. The problem is, with initial install, that the Google Toolbar would only work with my initial Google account and not the one associated with my domain, where my central email would be accessed.
This site gives information on how to change the Gmail button to act the same, but for Google Apps for Your Domain (cutely abbreviated GAFYD in the article):
http://tech.blorge.com/Structure:%20/2008/02/23/google-toolbar-for-firefox-make-the-gmail-button-work-with-google-apps/