I haven't come up with anything solid, but while I was experimenting I noticed that my version of TinyXML was out of date, so I updated it and rebuilt Afterglow. That's about it for today; I'll most likely spend the rest of today implementing the Afterglow configuration and flags system.
Incidentally, if you have any ideas for how to architect a rendering engine for a racing game, let me know. I've never done anything like it before, but the hardware demands are so simple that I shouldn't need LOD or even proper culling. I'm mostly looking for an architecture that will make it easy to use complicated materials as well as (hopefully stencil) shadows.