What are the best ways of absorbing, and maintaining, knowledge?

You may be very interested in a document I came across a while ago, which is one man's manifesto on note-taking that he compiled in a (free) ebook called "How to Make a Complete Map of Every Thought You Think." You can find it here: http://www.speakeasy.org/~lion/nb/

The program he sets forth is extreme, as he is quite literally trying to detail and commit to memory (on paper) his entire mind. But it contains a lot of useful advice on how to take notes that are useful, accessible, and memorable. I've implemented bits of his system and it has helped a lot in school - I've found that it's much easier and more useful to take notes when there is some method to the madness.

Oh, and if you are at all a visual thinker, Always take notes on paper. Paper offers freedom that lines of computer text simply can not: arrows, diagrams, color of pen, relative sizing of text corresponding to its importance, arrangement of elements on the page, all of these things are immediate, intuitive, and completely your own. I'll cite a paper that highlights the importance of this sort of visual language: http://www.stanford.edu/~rhorn/a/recent/artclNSFVisualLangv.pdf

I've also thought about this a lot.

My conclusions, in summary, are that the best way to know more stuff over the long term is reading ebooks and the internet and putting everything useful into an SRS.

Cornell notes, shorthand, mind-mapping, livescribe: who cares? You don't need to take notes. Any method of learning that involves writing down what someone says they read (it's called "university") is ridiculous. Almost anything that can be taught by a person can be taught better by a book.

Speed-reading: perhaps, I haven't done much research. Honestly, gathering new info is a tiny subset of the whole "learning stuff" problem. It's the easy part. The hard part is keeping it in memory, for which: SRS.

Mnemonics: this may be worth learning. However, most things which are worth learning can either be learned without mnemonics or only require extremely basic mnemonics (namely, linking / association). The stuff where mnemonics really shines, like memorizing long strings of numbers of decks of playing cards, is pretty much useless in real life. The stuff that's useful is textured data, data that's coherent and meaningful enough to not need mnemonic techniques (apart from simple linking/association), for instance math or programming or physics. You don't need mnemonics to learn the pumping lemma, but you do need an SRS.

One thing I've been experimenting with recently is to use SRS creatively. I add my own ideas as cards to an SRS system, and just read them every time they're due for review (failing them if the idea seems unfamiliar). Another thing I'm trying is to use SRS to re-expose me to things I've read. If you see a nice LW article, just up and copy the whole thing onto an SRS card, then just look over it when it's due for review. You can add notes to each card about how much time you should spend, like whether you should just skim over the article or read it in detail. If you're reading an ebook, just copy each section into your SRS as a re-exposure card (in addition to adding all useful facts in as active-recall cards).

Seriously, SRS with ebooks just completely subsumes all other techniques for learning stuff.

For making notes I wrote an open-source hierarchical plain-text editor Notilo. It is basically a Notepad with tree structure. There were a few similar programs, but none of them had all of the features I wanted (free, Unicode, saving in database, no special syntax). The program is not finished yet; it works correctly, but it should be more pleasant to use and better optimized for very large documents. (I have stopped the development when the proverbial 20% of features fulfilled 80% of my needs.)

In real life I keep a bunch of A7 papers (for US readers: a letter size cut to 8 pieces) in a plastic envelope and a small pen. The papers are small enough to put in my pocket and bring almost everywhere. Later I write the notes to computer and discard the used papers.

Recently I made a habit to write down almost everything I learn about programming (that's my job), because I have noticed a knowledge loss when I work with some technology, then a few months or years I work with other technology, and then I come back again. This didn't happen to me when I was younger, because when I moved to a new technology, I did not return to the old one, but these days I am using a few different technologies in parallel.

(Once I thought that having a "personal wikipedia" could be great, but I don't want to put private information on internet and running a web server on a personal computer makes it very slow. But there are some programs that provide similar function without the web server.)

Today the computer media are cheap and it is easy to record anything. Problem is, your day has only 24 hours and the Moore's law ain't gonna help you about it. It could be interesting to record every conversation you ever had, but when will you listen to them? And what is the point if you won't? You need to system to search your database; at least provide some keywords to each conversation, so you can search the keywords.

Recently I've been using Evernote to organize my notes. It has a nice phone app that I can use to take quick notes while away from my computer, a computer program, and a browser plugin that lets me clip articles. When it comes to notes I try to think that every time I record an idea I would have forgotten, it is roughly equivalent to thinking of one new idea.

I tend to write out outlines after I finish books or some interesting articles partially to see the arguments more clearly and to refer back to in the future.

It's always interesting/fun to go back browse old ideas I've forgotten about.

This post is quite old but I'm curious if you ever investigated incremental reading further. I'm an IR user and I don't think there is any more effective way of managing large volumes of learning. If you have questions about it I can answer them.

Example: Edward Boyden, Assistant Professor at the MIT Media Lab, recommends recording in a notebook every conversation you ever have with other people.

The link goes to Prof. Boyden's university profile, which doesn't mention his note-taking habits. This is all I could find after spending five minutes on Google:

"He was doing three students' worth of work," says Raymond. "Every moment of his day [is] action-packed." Both his advisors recall with a laugh Boyden's habit of taking notes on all his conversations and ideas. "He does this, so far as I can tell, every waking moment," says Raymond.

Does anyone here know where more information about Boyden's approach is to be found?

I find that annotating articles really helps me retain information. This was hard for me to do online until I found diigo.com. there are some other sites that are listed on wikipedia, but this one is the best IMO.

I'm currently working on a piece of speed-reading software. It works as a browser plugin, creating a floating window in which words flash a few at a time, so that you don't have to move your eyes, and to keep pace.

If people have ideas about features it should have, I'd be interested. For example, how valuable would it be to pause after each paragraph (or group of short paragraphs) and show some sort of summary? For example, it might extract all the proper nouns and low-frequency words and make a tag cloud.

I found it hard to generate a structure while listening to the teacher at the same time

You don't generate the structure and make annotations and summary during the lecture or reading, you do those afterwards during your review of your notes.

One key in studying is to not to try to do too much at the same time. Read, then go back and underline or take notes, don't try to underline during the first read-through. Review and condense/summarize then, not while taking the notes. During later reviews, just read the keyword and try to explain it from memory. Active, not passive - the more focused you are on what you are doing, the better you will retain it.

I note that you leave out recall.

You might want to do some research into "mnemotechnics". Also: Baddeley's model of working memory is quite interesting.