Google Guide
As most people use Google for the majority of their searches, I thought that my first post should be about this tool. It has its limitations (natural language searching being high among them) but it also has many features that most people aren’t aware of. Google Guide is an incredibly useful reference for making the most of Google. It could be a little long to read in a single sitting but it’s well indexed and easy to navigate so that you can go directly to the section that interests you. I would recommend at least looking at their Cheat Sheet and Calculator Cheat Sheet which have quick lists of the different operators you can use in Google and what they do.