Mozilla Prism is a nice way to browse all that API documentation and HTML user guides free of distraction. I have resorted to creating Prism shortcuts to almost all of the API documentation, HTML User and Reference guides. When I need to refer to a User guide, I just launch the shortcut, and all I see is that API documentation.
Not radically new, but beats launching a new browser instance to read these docs, and getting distracted by getting tempted to check email, blog subscriptions, etc.. etc.. etc..
Here is how it would look – This is an instance of Prism with the Spring Framework tutorial open currently – I can concentrate just on the tutorial, and not get distracted by anything else.