How do I find a keyword selector tool to help me determine what products are popular on the web?

I am really keen to set up another online business but need help finding a software tool. You may know this tool as the keyword selector tool, reverse search tool or keyword inventory tool. Using this tool, when you put a keyword in the browser it not only gives you the total amount of searches for that term for that month, but also gives you all the connected variables to that word. For example, if I put the word "dog" in the browser, it also gives me variables such as dog food, dog health, dog clothes, etc. It also displays the amount of searches for those terms alongside the words. The idea is to accurately find niche products/services to exploit on the web successfully.

Congrats on wanting to start a new web business.

I believe one of the types of tools you are looking for can be found at: http://freekeywords.wordtracker.com/

Good luck,
Lena