BG Renderer allows you to render your Render Queue items in the background while you can continue working in After Effects. It  runs as a dockable panel that is saved as part of your workspace. BG Renderer now comes in 2 flavors: Basic and Pro.

• With the all new basic version you can just render your queue in the background. We completely re-programmed how it works so that it is simple and easy and works every time.
• If you need options, then the Pro version is what you want.  Besides being able to set prefs for the render, the pro version offer the very powerful post render actions which allow you to get growl notifications, send email (with log), send sms and even iPhone push notifications when your renders are done or you have an error.  You can also send a terminal command to be executed after each item in the queue is done rendering and put the machine to sleep or shut it down. If you are using CS3 or CS4 and have CS5 installed, you can send your CS3 or CS4 render to the CS5 render engine to take advantage of the new 64-bit goodness while keeping your work project in the older version. Finally there is a new portable app/folder feature that makes it easy to create an ad-hoc render farm quickly by simply copying this portable app to all the machines on your network and just double-clicking it to launch the render on that machine.

Home Page - http://aescripts.com/bg-renderer/