dieseldick, this is a subject that ive had an interest in for some years. Theres no doubt that these experiences happen but what exactly that experience is who can say? Theres some anecdotal evidence that people who experience 'negative' NDE's actually go on to experience 'positive' NDE's given enough time.
The main argument that NDE's are no more than the product of a dying brain were made popular by Dr Susan Blackmore's book, Dying to live
http://www.amazon.com/Dying-Live-Susan-J-Blackmore/dp/0879758708
According to the sceptics, NDE's are the result of anoxia, hypercarbia etc. Many of these theories have been questioned since.
Vulcan makes the point that NDE's are a re remembering of the birth experience. This was a theory of Carl Sagan but people who have been born by caesarian section have reported NDE's with tunnel and light experiences also.
Personally Im an agnostic sceptic but sceptical explanations of NDE's dont cut it for me at present.
BTW im sozzled at the moment otherwise I might have had the inclination to post a few links, maybe tomorrow. ;-)