AuthorIT is a database-driven content management and authoring system that can produce print and web content as well as online help.
Doc-to-Help and Dreamweaver Deva Tools
Similar to RoboHelp, Doc-to-Help uses a relatively simple graphical interface to help you import documents and create an online help system.
Choose the right tool
Like any other development task, creating a help system for your applications requires choosing the best tool for the job.