Taking advantage of my regular gmvault backups of my Gmail account (which has been my main email account since mid-2007) I just made the following graph, which indicates the number of new email contacts (emails sent to people I had never emailed before) during each day, ignoring outliers, smoothing out trends, etc.
The graph as such looks relatively uninteresting, but armed with context about my last few years' of personal history (context which doesn't really belong in this space) the way the smoothed-out trends follow my life events is quite impressive (e.g., new jobs, periods of being relatively off-line, etc). Not much of a finding in these increasingly instrumentalized days, but it's a reminder, mostly to myself, of how much usefulness there can be in even the simplest time series, as long as you're measuring the right thing, and have the right context to evaluate it. We don't really have yet what technologists call the ecosystem (and might more properly be called, in a sociological sense, the institutions, or even the culture) for taking advantage of this kind of information and the feedback loops that it makes o possible; some of the largest companies in the world are fighting for this space, ostensibly to improve the efficiency of advertising, but that's the same as saying that the main effect of universal literacy was to facilitate the use of technical manuals.
Regarding the quantifiable part of our lives, we are as uninformed as any pre-literate people, and the growth (and, sometimes, redundancies) of the Quantified Self movement indicate both the presence of a very strong untapped demand for this information, and the fact that we haven't figured out yet how to use and consume it massively. Maybe we both want and don't want to know (psychological resistance to the concept of mortality as a key bottleneck for the success of personal health data vaults - there's a thought; some people shy away from even a superficial understanding of their financial situation, and that's a data model much much simpler than anything related to our bodies).