Runkeeper is a great service, but they don't yet provide a data export service. If you're like me, you want to be able to to have your own data on your computer to see your progress, do correlations, etc. This page will let you do that. Enter your Runkeeper username below and click the "Get CSV" button to get a CSV format file which can be loaded into any spreadsheet for analysis.
This only works with public Runkeeper data. If you'd like to keep your Runkeeper data private, I suggest making it public, getting the CSV from this site, and then making it private again.