Sparklines are small diagrams which can be inserted in a text. They give a fast impression of an evolution, so for instance this sparkline ▇▇▇▅▃▁▇▅▃▇▅▃ . It shows the number of views of this blog over two weeks.
A sparkline generator can be found here: http://www.datacollective.org/sparkblocks.html. And sparklines can be inserted into tweets!