Software features that change users' behaviour

Our new car has a splendid software feature that none of our previous cars have had. I don't know what it's actually called, but it shows the average miles per gallon (to one decimal place) on an LCD on the dashboard. It has completely changed how I drive.

I used to bomb around a bit too fast, because there's no point travelling when I could actually be doing the thing I'm travelling to a bit sooner, right? Now, I spend the journey with half an eye on the econometer (as I've been calling it - what is it really called?), trying to get the number as high as possible.

Living at the bottom of a hill in a housing estate means that I always get off to a bad start, but going down a hill in 5th gear with my foot completely off the accelerator makes the number get bigger. Driving slower makes the number get bigger. I even had a quick search on Google for how to go from standstill to 5th gear as economically as possible. I might even save some money by driving more carefully. Anyway, I realise I'm getting much too nerdy about this, so I'll move on.

The point of all this is that a really simple little thing of a software feature that I didn't think was even necessary has changed how I, the "user", uses the entire package. A couple of times in my career I have written software things that have had that effect on people. I managed to save Tracey at Manchester airport an hour of paperwork every day, which was really gratifying. I wrote a simple pool car booking thing on an intranet that reduced the hire car bookings from around 30 a month to about 1. I was part of a team that wrote something for a rail company that saved them more than what they paid us (for a couple of years' work) in the first month. There may be other features I've written that have made a positive impact, but I don't remember getting feedback about them.

So there we are, in a 10 year career, I can think of only 3 things that I've done that have made a really big difference to someone. I may be getting old and loopy or something, but I think that's a bit of a shame. I know I didn't get into programming for the benefit of mankind or anything, but it would be nice to do some more significant things (without necessarily becoming a nurse or aid-worker or something).

The thing is, I don't know which things are going to make the most impact. I bet the guy who invented the "econometer" won't know that his one feature has changed my driving for the better (when speed limits and cameras couldn't). If you know him, please pass on my appreciation.

[Update: Seth Godin suggests that putting a real-time mpg meter in a car would have an effect. It does!]
13 August 2005