Does anyone know if there is a tool out there that will spider a domain and calculate the keyword density or frequency of a certain key word or phrase? For instance, let's say I have a widgets site with thousands of pages. I want to know which page is the best candidate to be optimized for "purple spotted widgets" but I don't have time to sift through every single page and analyze the copy one at a time. Is there a tool that will do this for me? …preferably free, but I would be willing to pay for a very reliable tool.