Keyword Density Checking
These tools check for the occurrence and density of keywords in websites.www.googlerankings.com/ultimate_seo_tool.php
Measuring your PageRank
Tools that can be used for measuring the current PageRank of a web page.
Google Toolbar - installs a toolbar into your browser and includes the option of displaying the PageRank of pages you visit.
Predicting your future PageRank
These links provide tools that attempt to predict your PageRank. Note: The tools are for curiosity only and the predicted values are sometimes wide of the mark - they aren't really SEO aids.
Google Results for Multiple Countries
This tool allows you to see how a website performs in multiple countries. There is no single "google" and the results from Google data centres for different countries can be very different.
Find out who owns a competitor domain
This tool allows you to find out who own a domain. The report also provides an SEO rating.
Find Blogs on a particular topic
This tool allows you to find blogs on particular topics. Posting comments on blogs can give you free backlinks.