Web developers who want to add charts and graphs to their web sites have three options. 
1. Use server side generated chart images 
2. Use flash 
3. Use canvas + javascript

Option 1 is often the best unless you need some level of interactivity at which point you're stuck with choosing between flash that has problems with focus on linux, and has never been a favourite of FOSS developers, or using canvas + javascript with incomplete support for Internet Explorer through excanvas.  YUI-flot follows option 3. 

YUI-flot came about as an attempt to bring the popular flot plugin for jQuery into the hands of YUI developers, and in this talk, I'll cover a little bit about what you can do with YUI-Flot, and a little more about what I learnt while developing it.