When you get behind on your Google Reader feed it's next to imposible to get caught up and find out what's going on everywhere. Highlightr is an extension for Chrome that tracks the social media shares, likes, and ranks of posts from your feeds to help you quickly cut through the clutter.
Highlightr adds a small ranking number to each post and dims the colour on lower ranked posts. It's not especially helpful if you keep up with your RSS feed daily, but if you get behind it's an easy way to see what's trending and popular without digging through it all. The longer you use Highlightr the better it gets about ranking your feed.