Yesterday i got a request for a sample sparkline workbook at my PowerPivot and Sparklines .. the easy way blog post. I have created a sample sheet that looks like this:
And shows how it works.
You can download it at my skydrive: http://cid-7f4e0559cc74581a.skydrive.live.com/self.aspx/Openbaar/Sparklines%20sample.xlsx