Adding online help

Hi,

I have some context sensitive online help stored in a db table which I
display using Markdown.
This works fine but I was thinking of adding a complete Indexed type
help that could sort of double as a user guide for the app.

Can anyone recommend a plugin or something to prevent reinventing the
wheel?

Would a Wiki type plugin do a good job?

I cant find anything obvious by search the web.

Cheers
George