I spent a couple of decades writing in disorganized notebooks, never looking at them again. Most of that time I was into various 'obsessions' for weeks or months each—learning about some topic, reading everything I could get my hands on about it.
The last few years I've been making LaTeX PDF books, one for each year, and books for particular subjects, e.g. I have a book each for writing music, programming languages, maths, my programs, my essays etc. These split off from the current year's book when they get big enough. I'm only capable of being into 1 or 2 things at a time, but now when I return to a subject months or years later, the beautiful LaTeX book is there waiting for me. Often I've already forgotten most of what I wrote into the book before. I just wish I'd started doing that decades earlier!!
Also, I'm continually writing into a text file—every idea I have, quotes, links, ideas for things to do etc. Then every week or two I move stuff from the notes file into its appropriate LaTeX book.
Oh, and the movies/series I've seen in the last 10 years has its own web page[0]—the page I visit most often on my website, by a long way. I'd have forgotten the names of 95% of them if I didn't have that page.
My site was initially inspired by Bill Beaty's approach on amasci.com[1], of putting everything online, making your site your filing cabinet. I think I got sick of carefully-designed pages changing how they looked every time I saw them, or formatting breaking, so lately I've done most stuff in (private) ebooks, which maybe is a shame. Just my bad web-design skills I guess.
[0] http://www.adamponting.com/movies/
[1] http://amasci.com/faq.html A lot of great advice/wisdom on this page!