Hi Dave, I realize now that I didn't answer your main question. Sorry.
In my mind I have four uses for this system:
1. Gather everything in my computer in the index, as links, so that everything is accessible from one place. So my folders of images and documents are linked to from the index, as well as my work projects - TWs on topics where I gather larger amounts of info. Handy to say the least.
So yes, everything and every kind of thing, would be accessible, but not every little file would get a link, just folders, until I am working on a project and feel a link to this presentation or that TW is warranted.
2. Have a big version of a TiddlyWiki, where the majority of my topics hyperlink back and forth with each other, and get indexed in one central index. But in this case they link between multiple TWs rather than one, and get indexed in a central index. As Tobias wrote, when one wiki won't cut it.
3. As certain tiddlers get polished enough to share with others, I will export them as statics and publish or send by email.
4. Have an easy method of dumping and tagging deas as I find them in reading, browsing, philosophizing, etc. Open the index, search for the category in which to put the idea, create an external link in the index to a "letter" TW (if the idea is about the environment, I will make a link to an as yet uncreated tiddler in the E file), save and click the link, and create the tiddler there in the E file. If the tiddler already exists, I will just add the idea to the already existing tiddler. Long paragraph to describe it, but it is an easy process.
I should say that I came across this fourth function by going about it backwards. My original idea was to have any number of TWs organized by topic, and work on them as projects (thus the projects folder), and add tiddlers in each, and remember to link them from the index by grabbing the permalink of the new tiddlers. But then two things happened:
a) I was reading some great articles online at the Book of Life (
http://www.thebookoflife.org/what-is-the-book-of-life/), and wanted to copy and paste items from them into my system, but found that I didn't have TWs for those topics. I would have to first create new TWs, then paste. Too much work for every new idea that comes along. I realized I needed something like my old Braintags classic TW, where I could just "dump and tag." So I came up with the idea of doing TWs with letters and numbers so that no matter what new idea came along, I could just add it to the appropiate letter or number (C for courage, 1 for the book 1984).
2) As I was playing with my letters and numbers idea, my only thought was to have them as somewhat isolated from and unrelated to each other, but with links to all of them from the index. But then I discovered how easy it was to hyperlink between them if I put them all in one folder. [ext[Courage|./c.html#Courage]] is really no harder than doing hyperlinks in Wikipedia / Mediawiki, and not much more effort, mentally, than doing an internal link in a TW. I could even create a bookmarklet to wrap a topic iwth the link markup to make it even easier. And even better, I realized that clicking the link from the index takes me not only to the other file but directly to the tiddler or potential tidder!
So rather than start with the files and remember to add a link in the index, I now can start with the index, create a link quickly, and add the idea in the proper place. And I need not fear overwriting an existing tiddler, since if it already exists, I will be taken to it. A much, much better process for me.
I hope that helps. Blessings
Dave