Rob asked about the app I use for tracking my rides. I've been using Cyclemeter since April 2010, and have found it to be pretty much ideal for what I do. I don't want to have all of my ride data stored on a third party server (insert tinfoil hat conspiracy here, or, failing that, something grumbling about people monetizing my life). I like that Cyclemeter stores the activity data on my phone, and only exports it when I want it to, in the formats I choose. For instance, here's a view of the weekly data, going back to April 2010:
I had Cyclemeter export a .csv file with weekly historical summary data, then pulled that into Excel and made a pivot table to make some sense of it, then made a chart of that to show activity over time. Having access to all of my own raw data is pretty handy.