Martin Fowler is an author, speaker, consultant and general loud-mouth on software development.
He concentrates on designing enterprise software - looking at what makes a good design and what practices are needed to come up with good design. He has pioneered various topics around object-oriented technology and agile methods, and written several books including "NoSQL Distilled", "Refactoring", "UML Distilled", and "Patterns of Enterprise Application Architecture".
For the last decade he has worked at ThoughtWorks, a really rather good system delivery and consulting firm, and he writes on his site Martin Fowler.
Books: NoSQL Distilled, Domain-Specific Languages (Addison-Wesley Signature Series (Fowler)), Analysis Patterns: Reusable Object Models, UML Distilled : A Brief Guide to the Standard Object Modeling Language 3RD EDITION, Refactoring: Improving the Design of Existing Code, Planning Extreme Programming, Patterns of Enterprise Application Architecture
Video presentations: Three Years of Real-World Ruby, Agilists and Architects: Allies not Adversaries Presentation
See the entire list of Martin's video presentations here.