The Observer has an article on authors who have praised their own works on amazon.com.

Amazon reviews can be weird. I recently read one praising the Oxford Style Manual, with two or three spelling mistakes in it. My favourite was a student at a British university who praised his professor’s book on criminal law saying he slept with it under his pillow (perhaps this was written by the professor himself?).

Here it is:

bq. Reviewer: (lwa98rcl@shef.ac.uk) from Probably the best university in the world
Once again Mr Jefferson of the acclaimed law department within the University of Sheffield has produced a work of unsurpassable quality. Rarely has a book of such accessibility and depth of reasoning been available to undergraduates. Jefferson uses his inimitable writing style to maximum effect, sometimes humorous, sometimes heartbreaking but always lightning quick and razor sharp. Readers will feel priviledged to have read this book. I keep mine under the pillow.

(0 out of 3 people found the review helpful)

The book, Criminal Law by Michael Jefferson, is in its sixth edition and has a picture of Dixon of Dock Green, a 1950s/1960s TV policeman, on the cover.
Apparently it was amazon’s Canadian site that revealed the reviewers’ real identities.

There can be even more value in amazon reviews:

bq. [Lisa] Jardine, a former chairwoman of the Man Booker Prize judging panel, added: ‘In America, Amazon review-watching is a sport. There have been some fantastic indiscretions. One ex-wife of an American author put the history of his infidelities in her review of his book. It was breathtaking.’