MicrostockDiaries recently announced the launch of MicrostockCharts.com. It's a service that allows microstock photographers to record and plot graphs of their earnings. I guess the best way to learn about it is to read the full post on microstockdaires.
At the moment microstockcharts is simply a way for you to manually enter your monthly earnings, portfolio size and number of downloads etc. then plot graphs of RPI earnings and downloads. There is an option to make your charts public if you want to share them e.g. posting a link to your sales history on a forum.