Doc Searls, in a post in which he suggests Subscribe Sunday as a blog equivalent of Twitter's Follow Friday, references self-tracking - the practise of monitoring and recording aspects of one's daily life.
Spookily, about a week or so ago I started using Daytum again. Daytum is a web based tool for keeping count of pretty much anything you want and has a nice iPhone friendly mobile version that makes keeping track of things very easy. I had played with it a while ago but this time decided to use it seriously to track my caffeine intake and a number of other aspects of my life.
I guess self-tracking may seem a tad narcissistic to some but then it is in many ways a similar activity to blogging. I always used to justify blogging by quoting Plato's "an unexamined life is not worth living" and indeed "if it can't be measured it can't be managed".
Buster Benson does a pretty good job of explaining self-tracking and why it is worthwhile on his blog Enjoymentland and taking Doc's lead I too have subscribed!