1)   Document! X 5.0
Document! X automates the process of creating and maintaining documentation for a wide range of solution elements: VB.NET/C#/C++ .NET Projects; VB 5 or 6 / VBA Projects; Compiled COM Components and Controls; COM Type Libs, Databases, XSD Schemas.
documentation, .net, ndoc, help, f1 help, dynamic help, context sensitive help, chm, hxs, help 2,

 2)   HelpStudio 2.0
Generate help output in cross-platform plain HTML, HTML Help, Help 2.0 or printable PDF. HelpStudio seamlessly combines a feature packed WYSIWYG authoring environment with HTML based layout templates.
help, help tool, help authoring, .net, innovasys, pdf, documentX, online help, chm, hxs,

 3)   DC Help Authority 1.01
Help Authority is the only program that lets you create online help files from any point in your program. It helps you write multiple help topics, assign them to different areas, and link to them from anywhere, down to the smallest grid and column
help authoring, popup help, sensitive help, dynamic help, context hrlp, context sensitive help,