I just thought I'd share a bit of the nerdiness that occupies my mind.
As anyone who has ridden in my car knows, I keep track of the mileage of my car along with the cost of each fill-up of the gas tank in a little book in my glove compartment.
What you may not know is that I take that data and play with it!
A year or so ago, I found a website called Swivel which will take your data and make all sorts of fun graphs and charts with it. I've been keeping this spreadsheet since I bought the car, so I can call it fairly complete data. It shows me things such as the cost (in gas-cents) to run my car per kilometre (averaging 8.3 cents per kilometre),
the number of litres of gas that I use per 100 km (average 8.49 L/100 km),
and with the graphs and charts, I can see how this changes over time, and see trends - i.e. my mileage is decreasing, so there may be something wrong with the engine, or I can follow the gas prices over long time periods. If you look at the gas price chart particularly, you can see the slump in prices that began this fall preceded by the inflationary bubble prior to that.
All from my own data!
Obviously there are some spikes in the data and it can be a bit lumpy, but for viewing general trends it works really well. For all the time it takes to write this stuff down, it sure gives me something to chew on when I enter the data into my spreadsheet!
Check it out the full data here: http://www.swivel.com/data_sets/show/1011726