What are some alternatives?
When comparing SlimFAQ and Airim, you can also consider the following products
Dozuki - Dozuki is a web-based tool for creating and distributing step-by-step documentation.
Helppier - Helppier provides tools to create interactive user guides in minutes.
Manula - Manula is an online software for creating user manuals.
HelpNDoc - What is HelpNDoc ? Easy to use yet powerful help authoring environment which can generate various documentation formats from a single source.
FAR HTML - FAR HTML is a collection of help authoring and file utilities.