As far as I'm concerned, the to-do list is one of the greatest pieces of technology ever invented. The caveman who scribbled the first to-do list on a cave wall ("Kill mammoth. Domesticate dog. Drag home mate.") was an inventing genius Or maybe it was a cavewoman, and the list looked more like "Scrape hides. Gather herbs. Avoid getting dragged home by Thog." Either way, they were a genius, and they've made my life immeasurably better.
The next big advance in to-do list technology that has made my life better is the ability to keep one's to-do list on a computer and have the computer automatically update recurring tasks. It saves one from having to remember to list items that have to be done over and over again. Anyone who has any familiarity with Getting Things Done recognizes the importance of this: Not having to hold something in your head frees up mental space from remembering to do things, which can then be used for actually doing things.
From the outside, my life doesn't necessarily look like one where a to-do list or other productivity technology would be necessary. I work from home and my routine is largely the same, week-in and week-out. But look again: The inherent sameness of my days means I need to-do lists and calendars more because I don't have the mental cues (Monday was the big meeting about the Smithers account; Tuesday was when Charlie smashed the copying machine with a hammer) that help to separate one day from another. On top of this, I have a wife and 2 kids with major medical problems. This means I have all the usual responsibilities of running a household, cubed. I've got hundreds of things to keep track of over the course of a month, with consequences ranging from minor (garage full of recycling because I forgot to take the bin down to the curb) to potentially catastrophic (ran out of medication on the Saturday of a long weekend). On top of that, I have Asperger syndrome and an anxiety disorder. If I don't know for certain that I've got everything I need to do plugged into a system so that I can be sure nothing's going to slip my mind, it's disastrous for my mental state. I can't focus. I snap at people. I feel completely untethered from my routine and thus totally out of sorts.
For a long time I kept my to-do list in an app on my iPod Touch. I had tried close to a dozen different apps before I found one that suited my needs: To me, a task management app that doesn't handle recurring tasks is useless, one that only allows recurrences daily, weekly, or monthly is only slightly less so. Everything was fine until I dropped my iPod in the toilet and it stopped working. Since getting a new iPod wasn't in the cards right away, I started looking for an app that would let me keep my to-do list on my computer. I once again had to go through an extensive search before I could find one that met my standards. I finally found one: Producteev. I got all my tasks entered, repeating at their proper intervals, and everything was fine.
Then this Monday, Producteev had to migrate their software to a new system, and I haven't been able to log in since. I know there are things I need to do, but I can't get to my data to see them. I'll probably stick with Producteev once they get things up and running again, because checking out the competition during this outage has confirmed that Producteev still meets my needs the best. But I doubt entirely trust them again - there'll probably always be some level of underlying anxiety that this could happen again. I'm even entertaining thoughts of writing my own to-do list app just so that I won't be dependent on someone else's system. But I know that - as much as I might wish otherwise - it's not practical to build everything I need myself. It's just a hazard of living in an interconnected society, I suppose.