I'd like to share my specific motivation for writing Can the Chain Still Hold You?
I agree with Yvain that akrasia is probably a major reason that rationality alone doesn't create superheroes. You might be much better than average at making good decisions based on an accurate model of reality, but that doesn't mean you can follow through with them.
Many people report that their thinking is clearer and better as a result of Less Wrong. But despite our many, many attempts to hack away at the problem of akrasia (more: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10), I haven't heard of many LWers conquering akrasia.
But I still have hope that this is possible. In 2006, we finally got a decent psychological theory of procrastination, much better than the old decisional-avoidant-arousal theory. On the timescale of progress in psychology, 2006 is basically yesterday. The first book on how to apply this new theory to daily life was published in late 2010. There is no community of people systematically practicing these techniques and reporting their results.
So it seems to me there is a lot of low-hanging fruit to be scooped up in the field of procrastination research. If we try and test enough things, and especially if our tests our theory-guided, we may be able to learn new things and flip a few causal factors such that the chain of akrasia no longer holds us — at least, not as tightly as before.
I guess for me the power of Beeminder is in visualization and planning. For example now it is very calming to see that my exercise plan for previous 20 days progresses flawlessly. It also helps that some of my plans are decided in advance, so I don't waste mental energy and time deciding whether I should do something now or later.
Another useful technique, less reliable but more simple -- each evening I take a small piece of paper and write a "to do" list for tomorrow. I don't always follow the list, but at least I have a "default option" what to do next when I am undecisive. I would summarize both techniques as: "Make decisions in your brightest moments, and then follow them obediently." I guess my brightest moments are when I am going to sleep, because then the strongest temptation to procrastinate (continue web browsing) is over.
I don't pledge money or anything like this, because I want a motivational device, not a punishment device. (Sorry I am ruining your income model, but you made the rules.) As P.J.Eby says: "What pushes you forward, holds you back." The emotion I want is reassurance (I did it in the past, I can do it today and tomorrow), not pressure of fear. Because if I associate positive feelings with Beeminder, I will want to use it more; if I associate negative feelings, I will try to avoid using it.
Measuring goals in only half of the solution -- and you did it perfectly. Thanks! The other half is setting reasonable goals. This may depend on user's personality: my preferred method is to set humble goals, measure that I can achieve them, and then slowly increase them based on already collected data.