SparkStats is a little plugin to build sparkline-style usage graphs. And, use with sidebar widgets.
There are various options, including the number of days to display, the width of each bar, the height of the graph, colors, etc.
I’ve placed it on this site (for now).
More info on sparklines at Edward Tufte’s website, and the PHP Sparkline library by James Byers.
Tufte’s Beautiful Evidence is a wonderful book, as is The Visual Display of Quantitative Information.
