Eats, Shoots and Leaves
by Lynne Truss
This is book is a romp through the history of punctuation. It's very entertaining and contains a lot of examples of how to successfully or unsuccessfully use various dots to communicate effectively. This book left me with more idea of the importance of proper grammar and punctuation, I don't think it did much to help me improve my writing - but that is not a bad start.
The typsetting of the book is truly excellent, with small page size with around seven words per line, adding to the joy and ease or reading.