Groovy's Metaobject-Protocol provides a single point of contact for modifying the core behaviour of the Objects we create. John McClean shows how to use Groovy's MOP to perform AOP interception without proxyies or bytecode manipulation, and shows how the same is possible in Ruby and other dynamic languages.
Anil Hemrajani relates Agile practices to Java and several open source toolsets (Spring, Hibernate, Eclipse) designed to make Java development simpler. It's a high level overview of some free technologies used in web app development. Matt Morton liked this book, recommending it to technical managers and intermediate developers in small Java web development shops.