Yes, you can use google adwords for keywords ideas and than, you can plan for adsense. How is this idea!!!
You want a high click rate at .01 cent a click or something like only 10 - 20 clicks a day but you get paid $5 per click?
You have to research this yourself and test it out yoursef. But if you need tools to check out the amount of people looking for the specific keyword, you can get this free tool at: http://tools.seobook.com/keyword-tools/seobook/