I know this may be a silly question, but if I wanted to set up a "Help Center" for my applications, similar to the one used by GXT (see http://extjs.com/helpcenter/index.jsp), how do I do that? The help center looks just like the eclipse help documentation. Is this an open-source online-help module? What's the name of it?
The help center is a customized eclipse help documentation center. You need to create some custom eclipse plugins to do this. Check the eclipse documentation.