Google vs Yahoo Graph by seobench.com
Shows a graphic display of top 50 in Google & Yahoo with the sites that are in both SERP linked.

Keyword Density Analyzer by seobench.com
Enter URL, will calculate and return the keyword density of key phrases which are 1,2 and 3 words long.

Multi DC PageRank Checker by seobench.com
This tool will query the various Google Data Centers to check for any changes in PageRank values for a website. Helps you get a peek at your websites NEW PR during a PageRank update.

Alexa Page Ranking by Alexaranking.com
allows you to cut and paste a number of domians and get the 3 month Alexa Ranking or you can browse your harddrive and provide a list of domains. If you have a number of sites and you want to see the Alexa Rankings, this is the way to do it.

Alexa Rank Tool by SearchBliss
gives you the Alexa Web Rank plus today, 1 week and 3 months average rank.

Alexa Ranking by Evrsoft
allows you to cut and paste a number of domians and get the 3 month Alexa Ranking or you can browse your harddrive and provide a list of domains. If you have a number of sites and you want to see the Alexa Rankings, this is the way to do it.

Alexa Related Rank Check by 123 Promotion
gives you 10 seperate fields to enter domains and gives you the same day, 1 week ago and 3 month average Alexa Rank. It also shows the movement up or down in the last 3 months.

Backlink Check Tool by webuildpages.com
Shows backlinks and the corresponding anchor text. If the link has moved it shows NOT FOUND and if it takes to long it shows TIMEOUT.

Atom & RSS Feed Validator by feedvalidator.org
RSS feeds validator. It may validate any kind of RSS feeds, from the simplest ones to the most complex ones.

W3C Markup Validation Service by w3.org
The official W3C validator. A great help for making your pages W3C compliant.

Free Broken Link Checker by dead-links.com
check domain wide for broken outbound links. Very very very nice!

Free Link Checker by SEO-HighRankings.com
checks the URL of a single page for broken outbound links. This tools only checks the page you enter.

One Way Link Verify by We Build Pages
creates a list of links to check and allows you to export it. You then browse to the file and click on Go and it will check all your one page links. It gives you a report of them with PR and status if they are up. Very good tool to keep track of you one way links!

Online Free Reciprocal Link Checker by recip-links.com
checks the list of reciprocal you cut & paste into there form. It checks the page, not the whole site and reports back the URLs that it found had a link to your domain, the URLs that didn't have a link to your and any URLs that errored out.

Site Link Analyzer by SEO Chat
displays a list of internal and external links and their anchor text for input webpage.

Advanced Google Search Methods by AlgoTech
enter domain and keyword and select numberous searches includeding allintitle, allinurl, allinanchor, allintext, site, define, sponsored links and results with sandbox penalty suspended.

Free Google Keyword Ranking Tool by Nichebot
enter keywords, domain, depth of search (10-1000), any/all or exact phrase and choose one of the 101 Google country sites to search from.

Google Datacenter Watch Tool by McDar
is a tool that will let you do a search on Google at all the different datacenters. This shows whether the different datacenters are giving different different Ranking results for the same key phrase.

Google One Line Results by Google
enables you to view Google's search results with each entry on one liner.

Google Rank Position by PRSearch.net
allows you to enter a search term and the domain to search for. It returns the position that search term has on Google WITH, the number of entries that search term is indexed for, the PR of your home page, the size of file, the number of inbound links the site has and lets you know if you are in the DMOZ or Google Directory.

Google Rankings by googlerankings.com
searches for the entered URL and keyword in the first 1000 pages.

Free Keyword Search Tool by Nichebot
shows for entered keyword and simular keywords the number of times searched in 60 days according to WordTracker and Google results and Google exact results page numbers.

Free Meta Keywords Tool by Apogee-Web-Consulting.com
reads the meta keywords and gives you a hotlink with each keyword to Overture Keyword Selector Tool, Google AdWords Keyword Tool and Nichbot Free Keyword Identification Tool.

Google Adwords Keyword Tool by Google
provides you with 2 lists of words, Specific keywords that are that include your keyword that have been searched on Google and Similar keywords that are relevant terms searched by uses that searched for your keyword also.

Google Keyword Suggestions by SEO Chat
give you relevant and popular terms related to the keyword you search for. This tool queries information from Google searches for your keyword and determines popular and re-occurring terms and displays them with a field that shows there relevent per cent. Very good tool.

Google Suggest by Google
will offer completions when you type in your keyword for searches. I have found this very helpful in keyword mining.

Keyword Generator by Espotting Media
provides you with keywords from there PPC data base. Espotting powers over 1.4 billion searches every month across Europe. With offices in the UK, Ireland, France, Germany, Spain, Italy, Sweden, Denmark and Norway.

Keyword Popularity Tool by 123 Promotion
has made a number of changes to there Overture Keyword Popularity Tool. It now searches not only Overture's database but WorkTracker also! It looks like the same tool but the results in the search term field is an anchor text that opens up a whole new set of data and word mining possibilities. In the new set of data it tells you how many times Google and Yahoo find this term on the internet, there is a list of related words which is linked to let you conduct a dictionary.com or thesaurus.reference.com search or to research on one of the related words. Very nice tool, and very useful for copywriters.

Datacenter Quick Check by McDar
lets you add you URL and check all Google datacenters for BackLinks, PR and Ranking of keyword.

Future PageRank Tool by SEO Chat
will query all of Google's various data-centers and display your Pagerank value for each one. If queried during a Google update you will get a glimpse of upcoming PR changes.

Page Rank Tool by pagerank.net
shows PR on the differnet Google datacenters. Good for monitoring a PR update.

Check Rankings by checkrankings.com
Requires login and Google API. Very easy setup let you add up 10 keywords you want to tract in about 2 mins. Shows a one week or one month graph view for your Google ranking.

Advanced Meta Tag Generator by optimization-services.com
Advanced meta tag generator that give you fields for 19 different mata tags and generates the meta code for you.

Cache.it by cached.it
Shows PR, ping time, IP addy, what country the site is hosted in, thumbnail, meta tag text, cache status, Alexa ranking, and docs in different datacenters.

Code to Text Calculator by Stargeek
helps you avoid diluting your keyword relevancy by letting you know the ratio of your text to code. The higher the ratio of text to code in your webpage's the better.

Copyscape by copyscape.com
Copyscape is dedicated to defending your rights online, helping you fight against online plagiarism and content theft. Copyscape finds sites that have copied your content without permission, as well as those that have quoted you.

Google Banned Tool by 123 Promotion
This tool uses two methods to check to see if a URL you enter is in the Google database. Its a great way to check to see if you have been banned by Google for various reasons. If your site is quite new, you may also not show in the Google database. This tool is aimed towards people who think that they have been punished.

Meta Tag Generator by 123 Promotion
lets you fill in your webpage title, description, and keywords and then creates your tags for you.

Meta Tag Generator by SearchBliss
creates meta tags with title, description, abstract, keywords, robots revisit, robots index, rating, distribution, and Language.

Yahoo Rank Position by PRSearch.net
allows you to enter a search term and the domain to search for. It returns the position that search term has on Yahoo with, the number of entries that search term is indexed for, size of file, and the number of inbound links the site has.

Yahoo Search Rankings by yahoosearchrankings.com
searches for the entered URL and keyword in the first 1000 pages.