Well, there's 'The Diamond Age' by Neal Stephenson too. It features a world with complex technological and social hierarchies that can be related to the matrix concept. The book explores how technology shapes society and individuals in a world that seems to be part - digital, part - real. Another interesting one is 'Do Androids Dream of Electric Sheep?' by Philip K. Dick. Although it's more about androids, it also touches on the idea of what is real and what is not, which is a key aspect of matrix - related stories.
Sure. 'Altered Carbon' by Richard K. Morgan is a great one. It has a future world where consciousness can be transferred, which is related to the matrix idea of a digital existence. Also, 'Ready Player One' by Ernest Cline has elements of a virtual world that can be seen as a kind of matrix. In this book, the characters spend a great deal of their time in a virtual reality universe that has its own rules and power structures.