The graph above shows each instance that the book D3 Tips and Tricks was download from January 2013 to March 2015. It is best viewed in full screen by opening in a new window.
The main scatterplot has the day that the download occured on the X axis and the time (UTC) that the download occured on the Y axis. The time of the download is grouped into 10 minute blocks and where more than one download occured, the radius of the corresponding point is increased.
The line graph at the bottom shows the variation of numbers of downloads by day and the line graph on the right shows the variation of downloads by time of day (in 10 minute blocks).
Moving the mouse over the scatterplot will show the time and date of the point and the data is extrapolated onto the line graphs to show the corresponding number of downloads for the day and time.
There is an explanation of the code available in D3 Tips and Tricks or in the blog post here.