The documentation available on the boost website is... limited.
From what I've been able to read, the general consensus is that it is simply difficult to find good documentation on the boost::asio library.
Is this really the case? If so, why?
Notes:
Edit:
Some nice documentation on boost including a chapter on asio can be found in a (free) boost book at http://en.highscore.de/cpp/boost/index.html. The chapter on asio provides a general overview and then goes as far as how to develop your own custom asio extensions. Really fantastic effort by Boris Schäling!