APIMiner has just reached version 2.0, and if you don't know about it you might be missing out on a useful tool and a really good idea.
When you are documenting an API the least you can do is to list the classes, methods and properties. Each method also needs to have its parameters documented and JavaDoc is a good way to make your code more or less autodocumenting. But... wouldn't it be nice to add an example of the use of each of the API methods?
The big problem is that it takes time to find examples - a lot of time if the API you are documenting is a large one - like the Android API. This is where APIMiner comes in. It will automatically add an example taken from the code that implements or uses the API.
It scans through the API and makes a list of methods. It then scans a code repository to find uses of the methods. It then finds a block of code that shows the method in use and picks the best from all such examples. Finally, it inserts the examples into the JavaDoc.
At the moment APIMiner has only been applied to the Android API and you can use it either as a website or as an add-on to either Eclipse or Android Studio. In either case what you get is the usual JavaDoc plus a button that shows you an example of the method's use if you click on it.
APIMiner seems like a good idea, although carefully created documentation is still going to be a better option in all cases. It is a shame that currently it has only been applied to Android documentation. Perhaps the solution would be to turn it into an open source project. Currently the system is developed and maintained by the Applied Software Engineering Research Group (ASERG) of the Department of Computer Science, at the Federal University of Minas Gerais, Brazil, and is the product of work for an MSc thesis.