Hi,
I have a solution that I am quite happy with but it does take a little out of the box work.
Operational Mode:
Help files can be accessed individually in an ajax popup layer. They are called from custom html that shows the icon and calls the layer. In this manner, you can add context specific help icons throughout the application such as in query or form title bars, next to an attribute in the description field, in an html cell or wherever you want. I am a believer that help should be offered where and when people might need it. You can see how this works in the next two images:
http://iportcentral.com/iPort_Images/Clixon_Help1.png and
http://iportcentral.com/iPort_Images/Clixon_Help2.png
Context specific help files can be presented together via an external php page presented in a frame via a support menu item:
http://iportcentral.com/iPort_Images/Clixon_Help3.png
To Implement:
I use the highslide library but there are numerous javascript libraries that will allow you to show content in an ajax layer. You just need to add references to the js files in the startup.html file. I actually store the individual help files in a database driven cms website so that they can easily be edited without having to upload new bsv versions. I just present the external php page in the popup layer. This allows cross-linking between individual help files which is handy. You would have a number of options of where you store the help file content including in-line in the custom html.
For the comprehensive help file version, I just create an external php page and present the help topic menu and content in a frameset and then present the frameset inside AwareIM from a support menu item. As I am storing the help files in a database, obviously search capabilities could easily be added. Again, there are numerous approaches to this including ajax. (Check out codecanyon.net for low cost turnkey solutions)
Admittedly, this system takes a little more upfront work to setup and may require a little html knowledge but I believe that the end solution is pretty slick and very flexible. I have implemented it on a number of projects. There is an early version of this approach available in the AwareIM Toolkit that can be viewed at http://awareim-toolkit.com/features.html#Help. This version shows the help files in a popup browser window but if someone is interested in purchasing the toolkit for this reason, I would be willing to upgrade the version to use Ajax and provide detailed instructions on how to set it up.
Cheers,
Pete