Key search words and phrases in your "title tag", "META tags" (in the HTML script of your site) and body text are often very important references that search engines analyze when ranking web sites for search relevancy. Optimizing your title tags, meta tags and your body text for search engines gives it a much better chance of ranking highly for particular words or phrases that you would expect potential visitors to type in to search engines to find your site.

This is very helpful to find density of your targeted key words in web pages. It compares two pages. You can compare with your competitors web site.

Seoforum
Free Keyword Analyzer

Whatrank
This site provide your search engine positions for your keyword Try here Very helpfull!.