In these days of electronic devices, with their apps and software that help you get and stay organised there is still a place for pencil, pen and paper. So along with my smartphone and iPad, I still find that the simple 3x5 index card has many practical uses. There is a quality about paper that I love. I still have notes from decades ago and there is something about the feel, firmness and flexibility of paper that has outlived the old, large and small floppy discs and CD-roms of the early digital age. 3x5s will probably still be around when memory sticks and micro cards have moved on to their next stage of development.
I like to use 3x5 cards to capture and organise thoughts; make notes for talks and presentations; to carry with me as to-do lists and to file details of and from books - their original purpose of course was to index library catalogues.
I also like to use them to send notes to friends and colleagues. Heavy enough to sit on a desk they are great for short notes and personal messages and they can be popped into a small envelope to keep messages private. I find it useful to keep some in the car in case I need to leave someone a note that I called when they were out.
3x5 cards are of a size that makes them handy to keep in a pocket, purse or wallet. Their discreet size makes them practical when giving a speech as they look a lot less intimidating for an audience than walking forward with a bundle of A4 sheets. When using them for a speech I do like to make sure that they remain in the proper order so numbering is essential. Sometimes I couple them with a treasury tag, a much used device from yesteryear but now mostly used to keep batches of computer print-out paper together.
So here's a thumbs up, or more appropriately an index finger, for the 3x5 card!