Hi A.J. - thank you for your kind comments about our documentation! I am always thrilled to get positive feedback.
Currently we author the doc source files in FrameMaker, which organizes the individual files into a "book". If you are coming from Word, you would probably love FM. It has all the formatting features you love in Word but it is built just for this purpose, so it is more powerful and feature-rich. It gives you more control and more precise control over your docs. There is a bit of a learning curve to the app though. I had some training and would highly recommend it. A lot of the functionality isn't as visible or intuitive as you might expect and you might not discover on your own except after a lot of trial and error.
Using FrameMaker, you can print the "book" to PDF (hence, the User Guide). We use RoboHelp for FrameMaker to create the CHM file used on Windows and HTML files used on the UNIX platforms. RoboHelp does this automatically using the FrameMaker files, and also adds the breadcrumbs you mentioned. It knows not to include the page numbers or other PDF-related settings.
However, we plan to switch to DocBook soon. DocBook is a DTD set that includes both SGML and XML versions which are used to create technical documentation in a variety of outputs. There is a bit of a learning curve due to the back-end processes. It's not as simple as learning and using the tags, as some people have said about it, for me anyway (if all I had to do was write material, sure, it would be a piece of cake). However, this is a good format for source files if you need a variety of outputs. We already use DocBook for our SlickEdit Plug-In product. Eclipse works really well with DocBook for the Help integration.
Context-sensitive Help is another matter. In order to achieve this, currently we take the RoboHelp-generated output and process it against a script that Clark wrote, which pulls in all of the necessary API documentation and adds the two "Functions by Category" nodes at the bottom of the Help > Contents. I'm not sure about the details behind the script; it just works
For our SlickEdit Tools product (for Visual Studio), we use HelpStudio Lite. This is a tool that comes with the Visual Studio SDK and it is a really sleek GUI-oriented system. Everything is very easy to use and intuitive (like most Microsoft apps I guess). The only drawback to the Lite version is that you cannot create a PDF of the entire source. You would have to buy the full version of HelpStudio to get that capability. I've read the datasheet for the full version and it's packed full of features and looks awesome.
Thank you again for the feedback. Good luck!
Links for more info:
(FrameMaker/RoboHelp)
http://www.adobe.com/products/framemaker/http://www.adobe.com/products/robohelp/(DocBook)
http://www.oasis-open.org/docbook/intro.shtmlhttp://www.docbook.org/tdg/en/html/docbook.html(HelpStudio)
http://www.innovasys.com/products/hs3/overview.aspx