NoteAway - NoteAway is the simplest, most convenient way to take quick notes on OS X.
HelpNDoc - What is HelpNDoc ? Easy to use yet powerful help authoring environment which can generate various documentation formats from a single source.
JustNotepad.com - A free online notepad allows you to create any text or notes in your web browser.
Dr.Explain - Dr.Explain software is a help file authoring tool.
PlicPad - Shareable notepad without urls
CHM Editor - Best solution to edit CHM files