Keyword density
Cost: Free
After you type in the url of a page, you will see which keywords are used most frequently within the page. You can select the meta tag,alt tag, title, and select 1,2 or 3 listed keywords to view the results.
(Parandroid note: Many experts generally recommend keeping keyword density at 2%-8%.)
Keyword research tool
Cost: Free
This tool lets you query what keywords are used in your competitors' meta tags.
(Parandroid note: For Blogger, it's not quite competitive yet, but use this tool to find out how some good blogs with the same content as yours are set up.)
SEO Book's keyword suggestion tool
Cost: Free
One of the more useful and special free tools is the keyword suggestion tool for SEO BOOK. It not only gives you relevant words and phrases, but also shows you search volumes and suggestions from other keyword tools.
SEO Book's keyword list generator
Cost: Free Cost: Free
Type your url and a few keywords into the tool, and it will generate a list of relevant keywords for you.