Using the Google Keyword Bid Tool

As you can see in the image, you should be looking for a reasonable bar on the left to indicate that the search term is being used. Since Google doesn't quantify it for us, we just see "very low", "low", "average" and "high" volumes. However, since we only pay if someone clicks on the ad, lower search volumes providing only a few clicks per month could still bring us business. And those lower volumes sometimes mean less competition, thus lower cost per click.

The right bar shows the competition for the keyword phrase. Again, no quantification, but it gives us a comparison among our choices. It's apparent that, if we can find a phrase with a large bar on the left and small bar on the right, that we've located a gem of a keyword phrase.