I like thinking about interfaces and design for people with different sensoria -- the deaf, the blind, people with reduced or impaired vision, people with motor or perceptual disabilities, etc. I don't do much about this, since most of the code I write doesn't exactly have an interface (except for a game or two with a primitive CLI) -- but it makes for interesting design perspective. It's obvious that GUIs don't do great things for the blind, but how do you make something of comparable expressive powers that work thru a Braille / speech interface?
Anyhoo, a while back, I was ordering some Brailling stuff (stylus, slate) from the US National Federation of the Blind, and had them toss in something else from their catalog, mysteriously called a "3D marker". Since I got it, it's proven to be very useful. It's basically this stuff in a tube, with the consistency of Elmer's woodglue – except that it's not water-soluable, and it's not white-drying-to-clear, it's dayglo orange both wet and dry. Its purpose is not apparent, until you think of using it as a marker: Let's say you see fine, but live with someone who's can't see well. How do you label the jar of olives in the fridge so you can tell it from the jar of jam? Break out the screaming orange glue-marker, and write "olives" on the jar, or the lid. Takes about five minutes to dry, and then you can see "olives" written on it with the glue; someone who can't see, can feel the raised letters. Moreover, if you really want the stuff to come off, you pick at it with your fingernails and it does come off pretty cleanly.
Fine, but I don't live with anyone who's blind, so what's the point? Well, I have these jacks all over my laptop. They're theoretically labelled with tiny bas-relief icons of a headphone
Similar problem with the keyboard -- only one jack there, but the mini-DIN plug has to be lined up just right or it won't go; and the hand-motion for turning the plug thru a full circle while pushing into the jack, is not easy. But a dot of the 3D marker on the top of the plug makes it clear where it goes; a clue that's helped by putting a dot on the case just over the jack. What used to be a real pain, is now something I can do without even looking.
Now if only it were this easy to fix nasty computer interfaces.