All you need is a wire coat hanger and a few well-placed bends and you've got yourself an ergonomic laptop stand.
It starts with a small bend in the middle of the hanger's lower bar. Then, you fold each corner 30 to 45 degrees, about three inches up from the corners.
After that, it's just a matter of adjusting the bent corners to fit your laptop.
For more pictures of the entire process, check out this link.