Postrank is one of my favorite web services online, I use it all day long, every day. The service performs real-time social media metrics to show you how much discussion any post in any feed has received in comments, on Twitter, in Delicious, and across many other services. Then it allows you to view just the most-discussed stories from any source. It's great.
Now it's easier to use than ever if you're a Google Reader fan and on the Chrome browser. The company just released a Postrank extension for Chrome. It's not perfect, but it works much better than the previous Firefox extension did. You should try it.
There are two big improvements over the way Postrank has worked in the past and one new decision the company made that I believe is a mistake. The extension works best when in the "List" view, not the expanded view.
The performance of this extension is much faster than the Firefox extension. It won't slow down your browser and it tracks conversation metrics in real time.
Unfortunately, the scale of relative conversation is "contextual" which means if you have a folder of feeds from tech blogs, and you select the folder view, the relative conversation levels will be tracked across all posts from all sources. In other words, the most popular blogs will have written the most popular posts. That's not very helpful. Postrank is most useful when it shows you unusually popular posts per source. So don't show me every post that ReadWriteWeb has in my tech blog folder just because it's an unusually popular blog, show me unusually popular posts for each of the blogs in my tech blog folder. I hope the company will change that.
None the less - this is a great way to see what's most popular on a blog-by-blog basis, with that blog's regular audience of readers. It's also a good time saver for Google Reader users. Google Reader's own Sort by Magic feature is a cool way to see universally popular content, but if you're into blogs about real-time geofencing APIs with natural language processing, or the ceramists of Lake County, Florida, or whatever other obscure topic you might be interested in - now Postrank plus Google Reader will show you the hottest posts in those sectors. That's very nice.