I am currently reading (in French) "Voyager dans l'Invisible", by Charles Stepanoff, and it's really good ! I hope they'll publish an English translation soon enough. Translated into English, the title would be "Travelling into the Invisible : shamanistic techniques of the imagination".
Charles Stepanoff is a French ethnologist who spent years among Siberian and Mongolian tribes, studying shamanism. His book attempts to reconsider our western perspectives on shamanism, providing new theories about the phenomenon.
Stepanoff's work is dense and exciting. It starts with an almost philosophical reflexion, questioning our definition of "imagination" as the antagonist of "reality", showing how this now prevailing dichotomy was actually an exception in history (we owe the Greeks for that long lived bias), and how steppic and siberian cultures used to envision what we call "imagination" as an essential part of reality.
Hunter gatherers had to rely on imagination to survive in the real world : they had to imagine what their preys thought or hoped in order to catch them. So in a way, for these traditional cultures, it was a kind of 6th sense on par with the others. And case in point : if imagination was simply a kind of (harmful) irrealistic delusion, the evolutionary process would have got rid of it long ago. It didn't, although we evolved towards more "guided" imaginative processes (such as books and movies instead of dreams, meditative contemplation and childhood "imaginary friends" [by the way, the author describes the case of a shaman who started his career because he was seeing a purple "imaginary friend" coming out of the walls of his school !]).
Shamanism probably grew out of this pragmatic view of "imagination" (which includes empathy, planning, and strategy, e.g. seeing the possible futures) our Western rationalism did depreciate. In contrast with our modern despise towards imagination, Shamans may have been valued members of human societies from Prehistory onwards, which may explain why lots of the earliest prehistoric burials seem to focus on abnormal individuals (people with various malformations) who may have been shamans, or considered to be shamans [current shamans are often "recognized" through their unusual features].
Stepanoff distantiates himself from the 20th century interpretations of shamanism. Although aknowledging Mircea Eliades groundbreaking work in the area, he utterly destroys his association of shamanism with the search of transe and extatic experiences. Actual groundwork shows that shaman rarely reach truly extatic states. What they do is more involved with an active (and somewhat trained) use of imagination and visualisation, with an element of unpredictability and randomness.
The books then proceeds delving into case studies and developing the author's approach of shamanism as seen through the eyes of the shamans themselves.
I haven't finished it yet, but it seems to be an excellent piece of work, overall. The pace of the author is a bit fast. He launches tons of ideas without always taking time to develop them fully, which is sometimes terribly frustrating. If you want to go deeper, you're left with his sources, which I find a bit dry.
Some insights of this book may proove handy on "fortean" topics. In terms of religious studies, for instance, I can already see some interesting links to explore between shamanism and various "techniques" common in Asian religions such as Taoism, Vajrayana Buddhism, or Pure Land Buddhism. Some anecdotic facts seem to point out at common roots between shamanism and these systems. Nothing new, you may say, as plenty of researchers have already claimed that taoism had shamanistic roots. But this books provides with additional elements strengthening this case.
An exemple which especially struck me was that Stepanoff has collected lots of testimonies saying that Siberian animists believe that the Shamans have a different skeleton : they either have additional bones, or bones who have a different colour than ordinary bones.
If you have read the 4th century Baopuzi Neipian, Ge Hong's treatise on taoist immortals, you'll immediately notice the similarity with the Chinese claim that you must have "immortal bones" to become an immortal / fairy ("xianren", in Chinese).
Other fortean topics with possibe indirect links with the topic of this book (shamanism & imagination) : fairies, ghosts and spirits, mediumnism.
So if you read French, go for it. If you don't, hope for an English translation in the coming years.