My friend Drew just sent this one along:
I'm pondering things I might do with this. I've been using Data: URIs for one of my projects, they're pretty handy and both Firefox and Safari are more than happy to take ridiculously large ones (50k or more). Like Drew, I'm wondering what I could do with sparklines.
The first thing that comes to mind is a compact representation of BuildBot test results. When you look at the history of a single builder, a series of builds over time, what you care about it how the results have changed from one build to the next. I've been thinking about having the buildbot pay attention to things like when any given test starts failing or starts passing again, but until I get around to writing that code, you could use a sparkline to represent the test results in a compact glyph, and then just show the last 50 of those. The user could then scan them visually to look for changes.
I'm not sure where else to use them yet. I'm tempted to write a Nevow renderer to create them, though, because that would make it a lot easier to insert them into other pages. That would let you use some HTML like: <div nevow:render="sparkline" nevow:data="stuff" /> and then implement a data_stuff method that would return whatever you wanted to put into the sparkline.