Re: How to use TikiWiki for documenation?
Structures as in wiki structures.
Screenshot of one of a structures of our intranet:

You can place "toc" enclosed in flower brackets on any page in the structure to have the table of contents displayed. Like so:

You can display table of contents (the tree structure) of all your manuals (structures) in the homepage. Here's how --> check the reply by sdl
You could perhaps make use of dynamic variables or content templates to create a top navigational line that appears on all wiki pages and in there specify links to all the manuals so users can jump from one to another.
Or, have a horizontal menu for your site like:
