Lloyd Alvarez has collection of scripts for AE at his new domain, AE Scripts. He's also willing to host scripts. One useful script is the CS3 version of the BG Renderer, which automates running a background instance of the AE:
"It now runs as an embeddable panel that is saved as part of your workspace. It also utilizes the built in multiprocessing support that was added in CS3. This script takes whatever items are queued and ready in the render queue and sends them to render in the background allowing you to keep working in After Effects."
More scripting-related posts are here.