The Tibetan Book of the Dead, for instance, says that the soul is free from the old body for 49 days before it finds a new one to inhabit.
It's been many years since I read this book, but it had a big impact on me, and my spiritual beliefs. I read the Egyptian Book of the Dead, as well, but I was less inspired by it.
The Tibetan version would be better titled "The Book For the Dead", for it is written explicitly to help people through the trying period between death and rebirth. It is traditionally read to people upon their deathbeds, and shortly after they die, in the hopes that they hear and remember the instructions to guide them through the afterlife.
I remember that a goodly portion of the book is devoted to describing in great detail, various monsters, demons, beings and landmarks that one can expect to encounter during the time of death. This impressed upon me the cultural specificity of the book. I seriously doubt that Americans who have never once heard a Tibetan legend, fairy tale or religious myth, would encounter the same beings ... but rather, I expect we create our own demons to haunt us in the afterlife.
But apart from the Tibetan-centric nature of the descriptions, I felt a strong affinity for the general subject of the book, which was, roughly, that after death, you will be lost and confused in a strange land, beset by one frightening being after another, and gradually you will forget who you are, as this strange world slowly overwhelms you until, in terror, you happen to leap into the next comforting shell you come across ... a new baby.
With practice, meditation and study, you can, however, enter the afterlife fully conscious and aware of yourself, unafraid of the illusory beings around you, and calmly choose your next incarnation -- or not, as you see fit.
Maybe it is all just one more fictitious religious treatise to keep the masses malleable, distracted and compliant ... maybe. But it resonates with truth for me.