Engines of creation
Drexler explains how it is certainly possible to build molecular sized machines - our cells do so all the time. When we are able to control machines on this scale it will make possible a huge range of new products - for instance much lighter and stronger materials, leading to new possibilities in space travel. They will also be able to act within our bodies, curing diseases and leading to the possibility of extending our lives greatly.
Of course there are dangers to this technology, and Drexler spends much of the book discussing them. They would give any nation overwhelming power, and so we must hope that we have a responsible world order before such technology comes to pass.
The most interesting thing about reading a book like this is to see how the passage of 20 years has affected its message. In one chapter Drexler desscribes a network very much like the WWW, and one sees what hopes have been fulfilled and what has turned out differently. It's not really a book offering specific predictions about nanotechnology though, its would be more suited to those readers looking for a discussion of futuristic ideas in general.
Note: This book can be read online for free