How to generate lists of anything

A month back, I wanted to find out the areas of computer science which were similar to this happening field called "Machine Learning". I knew that "Artificial Intelligence" was very close to this, but I wanted more; I wanted a list of all research areas.
Yesterday, I was writing on human emotions, and wanted a list of many emotions that we felt. Googling "list of emotions" did not return any good results that I could use. Neither could I figure out areas similar to "Machine Learning" by a simple query search.
I needed a powerful tool which, when given a few terms, could generate similar terms which I was looking for.
This is where my awareness of online utilities helped me: I knew about this obscure tool called Google Sets which could do exactly what I wanted. Try entering a few states of mind like "happy", "sad", "angry" and see other emotions that the tool automatically generates. I say its nothing less than magic! This "Machine Learning" result will blow your mind off if you see how accurate the tool is, given that I entered only one example!