Here's a cool trick that allows you to render a LOT more efficient (meaning faster and/or cheaper). One of our users, Mike, used to do this a lot in his own pipeline and was kind enough to share it with us here.
Static camera shots
When you want to render an animation, and you have a shot where the camera is not moving, you can use this trick. When the camera doesn't move, it means that all the non-moving objects (like the background) are also not moving in the shot. This allows you to remove them from the animation, render them only once, and add them back in later with the compositor.
Depending on how many pixels the foreground elements take up compared to the entire frame, this can save you a lot of rendering.
Here's the video where Mike walks through the process with an example scene:
If you like the way Mike explains Blender, here's a link to his YouTube channel for more Blender tutorials: YOGYOG - YouTube
The scene on Blendswap: The Trippy Hallway
3D animated people from Renderpeople: Free 3D People