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We are working on a similar concept.
We aim to predict - Customer behaviors based on a function of their Geography, previous CRM notes, tags, liking and tastes. We call that as Interest-Graph and store them as nodes. We identify patterns.
We don't focus on leads; as we don't have much data. Rather repeat buyers, these are previous customers. We try to predict buying-behaviors from data in structured, unstructured sources, papers, CRM's and ERP.
So far we are able to predict: what campaigns might work on a group of customers, based on our graph data.
Look at the Compilers page, and all the real estate at the top devoted to parsing. Then look at Lisp ^_^. (You did do SICP under Brian Harvey, right?)
More seriously, at the very least I expect some of those pages to help me not overlook something important in the future in a project or two I'm thinking about. Those are of course fields where I have a grounding; if someone else looks at a page and feels completely lost, that's probably a signal to learn the foundations, which the notes can help in, as topics to search on, for judging books and other guides for their coverage (again touching on the completeness idea), etc.
The act of writing stuff down helps me organize thoughts and juxtapose related things as I'm learning them. There's definitely some content I haven't looked up again after that, but I surprise myself with how easily and thoroughly I forget something I once mastered, and how frequently I want to look up things exactly as I wrote them. I rely primarily on search for subsequent lookup. (Similarly, I'm also surprised at how frequently I Google for a question only to find that I had posted it years ago to a mailing list or StackOverflow - makes me feel very glad that I asked!)
I guess it depends on what you do, but as a generalist software engineer, I feel there's just too much crap to know, and I could never keep it all in my head.
I started using gitit since I had already kept my notes in a bunch of git-versioned text files (formatted in Markdown/Pandoc), so it was a convenient way for me to publish them for others to consume. It features feeds, TeX math, various output format generators, etc. I actually don't leverage much of the other wiki functionality (cross-ref linking, multiple users).
Markdown's a great format for most of the notes I keep (text, outlined text, quoted text, code snippets, links, etc.), but I have yet to find a system that beats LyX for writing TeX math. And of course both are useless if you want to just draw/scribble a diagram (Xournal covers that) or clip images you find (I use EverNote). Such is the scattered state of note-taking as I know it.
This guy  describes how he's using vimwiki as a lab notebook (HN discussion here ). I used that as a reference for my own and I'm pretty happy with that for some months already and started to use it as a personal knowledge management system as well.
Alternatively, searching for better tools/software: this guy's topic map blog is good (but prolific): http://tm.durusau.net/