XSnapshot is a framework for generating data transfer classes (which we call snapshot classes) based on domain model classes. Based on XDoclet markup, XSnapshot will generate snapshot classes and helper classes to convert between snapshots and models.
dtoGen is a java source generation tool that can ease the development of multi-tier systems by offering a reliable solution to obtain the data transfer objects out of the domain model objects without hand-writting additional code.
JOX is a set of Java libraries that make it easy to transfer data between XML documents and Java beans. You can think of JOX as a special form of Java Object Serialization, using XML as the serialization format.