Jon, Joe: some time ago I was playing with steamcharts (and, of course, how to create them in Excel…). They are visually interesting but they have the same problems that you’ll find in other stacked (area, line, bar) charts, plus they don’t have a base line.

To obtain the same effect that you see in the box office example you can’t have categories like “rss” or “search” or “documents”. Instead you should have projects A, B C and link specific feeds, searches and documents to each project. You may find that you spend 80% of your time in Google Reader, but is that relevant? Probably not.

Do you have a good alternative? The StreamGraphs that Joe cites do in fact look pretty, and they do help show totals, but I find it difficult to make sense of the individual items in the stream.

http://infoviz.pnl.gov/pdf/themeriver99.pdf
http://www.nytimes.com/interactive/2008/02/23/movies/20080223_REVENUE_GRAPHIC.html
http://www.leebyron.com/what/lastfm/

We use stacked bars, usually 100% stacked bars, but they typically have only 3 or maybe 4 segments. We use them to show student assessments broken down by category (e.g. “Proficient or Above”, “Almost Proficient” or “Far Below Proficient”), and usually show two years next to each other as a comparison. What we’ve recently done to make them more useful is to float them so the base of the “Proficient” segments in the two years match, making it easier to compare the trend of results above and below the cutoff. Sometimes there might be a number of sets of these bars, to break down subcategories of students for example. Even a whole row of these stacked bars is pretty clear, and probably would be even if we shrunk them down to “microcharts”. A quick scan immediately shows where there are “significant” differences from the other categories. Highlight lines could also be used, such as a proficiency target goal, running across the chart.