One of the most useful options I used when doing online research was the discussions option on Google. A few months ago, Google decided to remove it. Install this extension and it’ll add it back to your searches.
It’s really useful when you’re trying to do research on products. Right now I’m trying to find out information on CEL codes for my car. Without the discussion filter, all I see is links to auto parts stores. That doesn’t really help me find out what’s wrong with my car. I need to find out what part I need first.