Some time ago I wrote a post about my workflow to find image references and general information, useful when you are in the researching phase of your work.
I’ve found a nice tool of Google which helps you to find information related to one topic written by you.
For example, if you need references of American cars, but you only know the companies “Chevrolet” and “Buick”, Google gives you related companies of American cars.
It’s very useful!