Near death experiences (NDEs) are highly subjective, but longtime death and dying expert Elizabeth Kubler-Ross co-authored a nice survey of many NDEs, and summarizes the commonalities. Life After Life: The Investigation of a Phenomenon–Survival of Bodily Death is a very interesting study.
Also, the co-author wrote a follow-up book of Reflections On Life After Life: More Important Discoveries In The Ongoing Investigation Of Survival Of Life After Bodily Death.