If case you haven't noticed - YUI Charts hit the streets.
As with everything new, it's best shown and understood by example. So here's the simplest example of using a pie chart. Basically I took the example from the YUI page, changed all the paths to point to yahooapis.com (where YUI is hosted for free) and stripped everything that could be stripped (there's even no html or head tags, but turned out the body tag is required). The result is a short html with all dependencies satisfied.
OK, so here's the example, grab, paste, customize: