List Maker Tool

[Skinner]

A while ago someone posted a tool (I think was a google tool) where you put a few words in in and it generated related words.

So you put like

Cat
Dog
Mouse
Rat
Bird

and it generated a list like

Cat
Dog
Mouse
Rat
Bird
Goldfish
Hampster
Gerbil
Turtle

or something along those lines.

Anyone have any clues ?

 

[Skinner]

I found what I'm looking for here http://googlesystem.blogspot.co.uk/2012/11/google-sets-still-available.html