Performancing, the people who brought you the Performancing blogging extension for Firefox, have launched a new web service called Performancing Metrics that aims to provide "professional grade blog statistics" for serious bloggers. Performancing Metrics can handle multiple blogs and will aggregate data from all of your blogs, generates RSS feeds so you can keep an eye on your stats easily, and shows AdSense data and search engine traffic. It's entering a market currently occupied by Mint and, though it's not geared specifically to blogs, Google Analytics. Performancing Metrics is currently a free, open beta; no word on whether the service will still be free once it's out of beta.