The -use option to javadoc can greatly simplify the life of someone attempting to understand your code. It's especially useful with developer versions of javadocs which should also use the -private option.
-use Includes one "Use" page for each documented class and package. The page describes what packages, classes, methods, constructors and fields use any API of the given class or package. Given class C, things that use class C would include subclasses of C, fields declared as C, methods that return C, and methods and constructors with parameters of type C.
For example, let's look at what might appear on the "Use" page for String. The getName() method in the java.awt.Font class returns type String. Therefore, getName() uses String, and you will find that method on the "Use" page for String.
Note that this documents only uses of the API, not the implementation. If a method uses String in its implementation but does not take a string as an argument or return a string, that is not considered a "use" of String.
You can access the generated "Use" page by first going to the class or package, then clicking on the "Use" link in the navigation bar.