Last.fm Heatmap Calendars (fullscreen slideshow available here) [flickr.com] by Martin Dittus is a collection of static visualizations showing the individual listening habits activity of around 70 different last.fm users, encompassing over 8.7 million individual songs played.
Each visualization is a structured heatmap that reveals the periodicity of music listening, such as years, months, day of week, hour of day. A year of data is arranged in a row, grouped into 12 horizontal blocks, one for each month. In turn, each month is organized by an inner grid: 7 columns for the days of week and 24 rows for the hours of day. The color coding shows the measure of relative intensity, ranging from grey over green over yellow towards red. A light grey strip highlights the most active hours of the day across the entire period.
This visualization is able to reveal lunch breaks, dinner, commutes, new jobs, busy weekends, holidays, ... as long as it happens regularly and somehow interferes with one's music listening. They become particularly interesting when cross-referenced with the actual user's perception, such as for user David Singleton, who described his personal interpretation of his last.fm diagram on his weblog.
More testimonies from last.fm users can be found here.