Powerful canvas based graphing library that includes support for Venn Diagrams

Smoothie Charts is a really small charting library designed for live streaming data. I built it to reduce the headaches I was getting from watching charts jerkily updating every second.

Tinycon allows the addition of alert bubbles and changing the favicon image. Tinycon gracefully falls back to a number in title approach for browsers that don't support canvas or dynamic favicons.
Alerts in the favicon allow users to pin a tab and easily see if their attention is needed.

lots of different graph types. free for non-commercial. $49 GB Pounds for commercial