"...small, high-resolution graphics embedded in context of words, numbers, images. Sparklines are data-intense, design-simple, word-sized graphics."
Neat.
Update: Nelson writes, "The last thing I want when reading a paragraph is a tiny little data display breaking the flow. The sparklines look fine when they're by themselves as part of a tabular display. But in the middle of a paragraph they call too much attention to themselves." [and more...]