This particular tool tells you phrases that are "buying keywords," meaning if you rank highly for that particular keyword phrase you can be safe to bet that it can bring you a decent amount of sales for whatever you are promoting, especially if it is "Targeted Traffic".
The tool requires no installation, free to use, and can be found here: Detecting Online Commercial Intention: Audience Intelligence: adCenter Labs (Not An Affiliate Link)
This tool isn't always right when comparing it to the CPC rate, as well as the amount of ads for the particular term, but it definitely is worth using.
It should be pretty clear on how to use it, but if anyone has any questions about it i'll answer them if you plan on using it.
Hope this helps!