Fitbit + beeminder (fitbit to track steps, beeminder to ensure you walk enough)

-KeePass

-Gmail Smart Labels (invaluable for me since I get a lot of newsletters and similar bacn)

It's quite hard to think up examples - what springs to mind is stuff like setting up good habits (exercise, eating, etc), which in truth require most of the effort to get started - however they do of course require ongoing maintenance.

One-time fixes with permanent effects are harder to recall, maybe because they don't require any thought to maintain. The main categories there would be:

- physical stuff you buy

- changes to your digital setup

- skills or mindsets you adopt.

Let me see:

- spending time learning keyboard shortcuts for your most-used applications. Even better, customise them so they meet your needs.

- set your home screen on Chrome to be your Todo list (Trello for me). It's the best place to start your day.

- a recent one: getting an extension like "controlled multi-tab browsing" which lets you put a limit on number of open tabs (for me, 8) seems to cut down mindless surfing quite a bit.

- reading Getting Things Done will permanently improve the way you approach tasks. Best insight from the book: when faced with a large task you keep putting off, define the next concrete step to take.

- make your email communication more efficient. Eg, when asking someone for meeting, suggest 2 or 3 times in your first email - this saves the back and forth on when and where to meet. Focus on specific, direct questions.

- useful mindsets to adopt: assume "willpower" doesn't exist - to change habits, focus on changing your environment and observing your emotional cycles. Joshua Spodek's blog has lots of good material on the second part. Key point is that getting pumped up and excited rarely works long-term; beating yourself up never works. Be patient with yourself, observe what situations make you slip up from habits, rationally think about how to deal with those situations in future. I call this a "structural fix" because once you learn these principles, you won't forget them.

Excellent list! I'd add:

- Get evernote premium and create the habit of putting every interesting thought down on any of your devices (pc, web, smartphone, tablet, etc)

I'd intended to find/post some examples here when I saw it a couple of weeks ago so thanks to Sebastian for pointing it out again. Here are a few that may help some people:

1. Spaced Repetition: for times when you have a large number of items you wish to learn (for example vocabulary for a language) spaced repetition is one of the most efficient techniques. This post isn't the place for describing it in great detail, but the principle is that you want to test yourself on every item at roughly the time when you start to forget it. Various software packages automate this very effectively: I recommend Mnemosyne: http://mnemosyne-proj.org/ but there are a handful of other robust packages doing the same job. At the moment I'm using it for vocabulary in various languages.
2. Keyboard shortcuts: Isaac Lewis mentioned this already, but it's worth repeating - by learning a dozen useful keyboard shortcuts you can speed up many of the things you do every day. Plus if you usually use a laptop trackpad rather than a mouse, this causes less strain for your fingers. http://support.microsoft.com/?ln=en-gb contains shortcuts for various Windows OSs.
3. Only buying healthy food from the store: you can have a much healthier diet (whatever "healthy" means in the context of your lifestyle) if you simply do not keep any unhealthy foods around the house. Any temptations are easier to resist whilst shopping at the store than when you're hungry and about to choose something to eat...
4. Compile a list of things to take when travelling: depending on the duration/location/purpose of the trip you'll need/want different things, but it's handy to have a checklist stored away everywhere so that much of the thought required during packing is reduced to "toothbrush/toothpaste? Yes, I'm staying overnight. Passport? Nope, not going abroad. ..."
5. Speed reading: this is a skill that takes seriously minutes to become proficient in. Lingholic has a summary here: http://tynan.com/community/40573 (scroll down a bit). Make a note, and follow the instructions whenever you have 20 minutes of time/energy to spare.
6. Trying new things once: many things have little downside to trying (e.g. new foods, new activities, new routines, ...) so they're worth trying, just once (or for a week or whatever is appropriate) to see how well they suit you. You might like it, it might be a successful experiment with a negative result, or it might give you an idea of something that you really do like.