This is the Flotr for Prototype.js example index page. Here you can find links to various Flotr examples. Each example emphasizes a certain feature, but I think it's useful to read and understand all of the examples, even if they're of no use to you. Just to get a better understanding of Flotr.
If you want to play more, go the playground Flotr Playground.
Can't find what you're looking for? Check out the Flotr Documentation.