Got some time on you hands?
If you have a website and you want to see how many people are search the web, and using what word, so perhaps you can target your audience in a different way then you need the:
Google AdWords: Keyword Tool
Although this is designed around adwords, it is using the hit rate of search words used by web users. You can check how popular the keywords are by country and, if you are targeting mobile users, then only those users.
You can check your website tot the competitions request for a particular word.
Essentially this gives you an insight into web users, the search they are using on google, and how your site stacks up.
But remember I did say do you have time on your hands.