I've finally purchased a Director book and am now plowing through it, mostly skipping the things I don't need (ie Shockwave). I've gotten far enough in it that I've started the beginnings of the actual frontend, and as I progress further through the book I'll be updating the frontend accordingly.

The other thing that I've finished is a first draft of the XML structure used by the frontend, with a sample shown below:

<arcade>
  <systems>
    <system>
      <name>Arcade</name>
      <emulator>Arcade:MacMame</emulator>
      <games>
        <game alpha="D">
          <name>Donkey Kong (US)</name>
          <publisher>Nintendo of America</publisher>
          <year>1981</year>
          <rom>Arcade:Roms:dkong.zip</rom>
          <screenshot>Arcade:Screenshots:dkong.png</screenshot>
        </game>
      </games>
    </system>
  </systems>
</arcade>

This may of course change depending on what I may want to add, or what is easier to parse in Director, but for now, it seems like a pretty solid base to work from.