Lloyd Alvarez has released a script that allows you to render in the background while continuing to work in After Effects 7. If you have a multi-core or -proc machine, you can render multiple frames at once for a substantial speed boost, all without any noticeable impact on your interactive work in the foreground.
Since The Guide recommends conforming your film in After Effects, which inevitably leads to some serious render time, this script is a DV Rebel lifesaver. It's also a glimpse into the largely untapped power of After Effects scripting. Nice work Lloyd!