This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
Although using the online pages will ensure you always get the most up-to-date version for that major version (Java 6 in this case) it's good to also have a local copy, in case you don't have a working Internet connection. I even put the Javadocs on my USB stick so I have it wherever I am.