I try to make a tool for webdesigners. The web designer put some keywords in the form, and my script (tool) crawl the web and get information about SEO for my costumer. The tool show to the costumer informations like the keywords more in use, description, average pagerank, etc.
After I give this information to my costumer, I invite him for they do a site optimization, and if they do the optimization, in the end I advice him what changes they have to do in meta tags, and I present some solutions, like the best description, the best h1 etc.
But for I do a best work for him, I have to get the best keyword to show in my optimization.
If in the beggining of the tool my costumer search for "mobile phone", in the end of optimization I have to get from somewhere (script or api) the top keywords for mobile phone, like mobile phone accessories, best mobile phone, etc.