Michael Sippey recommends a couple PIM apps. Simson Garfinkel's Sbook5 looks interesting (stores data in XML), but don't know whether it makes it easy to associate records like Wi Ki (e.g. it should be easy to jump from a person's name in a generic note to that person's Address record, or all other notes mentioning him, etc.).
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If you use titles well in AZZCardfile, then you can get to a filtered list of cards quickly by typing just a few characters. Of course, it would be great if I could combine this with Wiki title markup and jump between cards...
To put a fine point on it, what I'm really looking for is a Rich Client (even single-user! gasp!) Wi Ki, that avoids any kind of mode-switching. I was running usemod locally under apache, but as a local note-taking mechanism the mode-switching (click, find the point to insert text, write, click submit, wait, refresh the screen, etc.) was just too painful...
I should do a screen mockup and post it on theobvious as a Request for Application. 
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Random thoughts: (--Bill Seitz)
Kinda reminds me of Hyper Card! You might also want to talk to Jeremy Bowers.
Theoretically you could have a single back end with both browser/Wi Ki and Rich Client front ends.
- how important is text styling (bold/italic, bullet points) to you?