Feedburner standard edition allows you to chart the circulation data of your feed for the last 30 days at maximum. Would it not be nice if you could see the Feedburner counts tracked on chart for the last 3 years!
JoostDeValk has used the FeedBurner Awareness API to extract the circulation data for a blog for a given period of time and chart the feed. Now it is easy to see how your RSS subscribers have progressed over time.
You simply need the FeedBurner name of the blogs, the timeframe you want to plot and the size of the widget that you can place on your site. They also have a tool to let you compare the FeedBurner history of multiple feeds.
Get one for your site too…