For me, part of the art of reading is note-taking. I started taking notes thanks to The Well-Educated Mind which gives very specific guidance for effective note-taking. This was supplemented by suggestions in How to Read a Book. While and since reading these books I've been experimenting with different formats and techniques. My main challenge has been learning the difference between that which is interesting (i.e. everything) and that which is essential (which is quite a bit less than everything). This is most easily accomplished with books I own, as I can underline as I read and then go back and take selective notes based on what I underlined. When I don't own the book is when I can really go overboard and take notes on every little item because I don't know if it will be important later. On the other hand, those details can lead to interesting insights (like hands in The Island of Dr. Moreau). It's more of a question of how much time and energy is available, rather than the usefulness of more or fewer notes.
A technique I particularly like is to summarize a chapter in sentence form. Like our high school English teachers tried to tell us, paraphrasing really does help us to understand and remember what we've read. It requires quite a bit of mental effort to condense and translate a piece of writing into our own words, which is probably exactly why it helps us remember it. It's like the difference between seeing how something is made and making it yourself—you're far less likely to forget your own creation. It's also the first step towards discussing a work with others.
Another thing I've discovered lately is that one format does not work for all books. Fiction necessitates a lot more quotation than non-fiction, so I generally write notes and summaries on one page and quotes on the facing page. Non-fiction is less quote-worthy and more note-worthy, but equally worth summarizing to get "the big picture." As I get into other kinds of literature, I am sure I will find that they naturally invite other forms of note-taking.
Stefanie has mentioned that she rarely looks at her stacks of notes but I'm finding mine quite useful so far. If I need to look something up I am more likely to go to my notes than the book itself. If I do have to go to the book for more elaboration, I know exactly where to go because I take the trouble of scribbling down the page each note comes from. Not only that, I am now copying out tables of contents, with page numbers from the text and for my notes on each chapter. Notes that are easy to find are easy to use! And it probably goes without saying that notes are invaluable for blogging. You don't think I write those long-winded book reviews from memory, do you?
Below is a snapshot of my notes from Roberts' A New History of the World. I've got it down to a system now, which makes taking notes more enjoyable. It certainly does require time and effort but with my swiss-cheese brain I would have a hard time remembering and grasping the overall import of what I read if I didn't write it down in one place. I actually attempted to read Roberts without taking notes (though I did underline), and realized that I was losing the sense of relation between what I was reading now with what came before (kind of important in history!). So I got out a fresh new moleskine, slapped a picture of Herodotus on the front (I love being a nerd) and got busy with my pen. Next stop: Ur!
