Software Architecture in Practice by Len Bass, Paul Clements Rick Kazman Addison Wesley 1998
ISBN 0-201-19930-0 From a review: A significant book on the practice of software architecture. Should be read by anyone who doesn't think that a Software Architect is an elitist scum and something evil to aspire to.
Who do you think need it, that won't read it?
See also: ProductLineApproach, AttributeBasedArchitecturalStyles, CoreAssets