Like Karin, I store any articles, handouts, etc. electronically. When I take notes at a conference or webinar I enter these notes on my computer and store them in a file appropriately named for that material. It does take time to enter this information into the computer but it is time well spent from my perspective. As far as my books, manuals, and the like I keep them organized on my bookshelf. I never throw any of that away because, just as you stated above, the minute you do you will need it. Of course, if something is outdated and the material no longer applies, I toss it.