Uses of readObject/writeObject in Serialization

I was going through this article to understand more about Java Serialization process. When it comes to uses of readObject/writeObject I could see two use cases:

1. We can use writeObject to encrypt the byte code before it gets serialized. From the security point of view, that's good thing.
2. we can use readObject to execute any specific piece of code that need to execute immediately after deserialization, and off course from poin#1, we can even use readObject to decrypt the byte code that was excrypted while serializing the object.

Is there any other practical scenario you've come across while serializing/deserializing objects by writing customr readObject/writeObject method? Or If you could point me to any place where I could see some decent and practical uses of readObject/writeObject?

Custom readObject methods are also useful when you need to initialize transient (non-serialized) fields after the object has been deserialized.

BTW, check out Effective Java, Chapter 11 (I'm not sure what the chapter/item number is in the 2nd ed.). It's an excellent read on serialization.