Whois and Reverse IP Lookup:
Whois Web Hosting Info – This tool not only allows you to check domain whois, you can also use it to do a reverse IP lookup. All without logging in!
Keyword Research:
Overture and Google Keyword Suggestion Tool – Combo keyword tool to gives the searcher one-click access to all the popular free keyword research tools in the market. Great for quick keyword research.
Keyword Discovery – This tool uses the keyword discovery API to return data for Google and Yahoo search.
WordTracker – For extensive keyword research, this is a great tool that offers one the ability to perform detailed keyword research for SEO and PPC.
Estimated Search Traffic by Ranking Position – Get approximate clicks for your keywords in Google, Yahoo, MSN, and other search engines based on the number of overture searches the term had last month.
Link Research:
Inbound Link Quality Tools via Search Engine Watch
It is a measurement based on points given for each dir.yahoo, dmoz.org, .edu, and .gov link. ILQ gives you an indication of the quality of inbound links a web site has … dir.yahoo links get 1 point, dmoz.org links get 30 points, .edu links get 45 points, and .gov links get 67 points.
There are different web based tools to track these high quality links in a variety of ways. There is the ILQ Rating Tool, ILQ Directory Search Tool, ILQ Directory Search & Buy Tool.
If you use Firefox, I recommend the Firefox Extension. This extension can be customized to show only the types of links you are most interested in tracking.
SEO for Firefox Plugin: This firefox plugin enables web researchers to quickly access the following information from within the search results – Google PageRank, Age, Links from Yahoo! linkdomain, .edu Link from Yahoo! linkdomain, .edu Page Links, .gov Links, Yahoo! Page Links, del.icio.us bookmarks, Technorati blog links, Alexa ranking, Google Cache, pages listed in dmoz, Bloglines subscriptions, dir.yahoo.com listing, and WhoIs.
PR Prowler – Scour the net for the most authoritative links for your industry based on PageRank.
Search Engine Position Tools:
MarketLeap Keyword Verification – Checks top 30 ranking across Google, Yahoo, and MSN.
Google Keyword Analysis Tool – Outputs Google data for the number of cached pages, number of backlinks, PageRank, and AllInAnchor. Also returns number of backlinks found in Yahoo.
Google Dance – Check rankings of top ten sites across different data centers.
Agent Web Ranking – Professional search ranking software that tracks search positions over time.
Back Link Tools:
Neat-O Backlink Tool – checks your backlinks (only showing one backlink per URL that links to you) and shows the link text used to link to you.
Check Unique Backlink Domains, IP’s and Age of site Tool – A 3 step tool. In step one it shows you a list of the URL’s linking to you. In step two it checks the IP’s and groups the URL’s by IP’s. In step three it checks the age of the websites that are linking to you.
Class C Backlink Analyzer – Type in a URL and get a report that analyzes C Class backlinks and ratios.
Website Tools:
Copyscape – Search for possible copies of a website.
Keyword Density Analyzer – Analyze the keyword density of your pages for optimal on-page factors. Keyword density should be around 2-3% for best results.
Google Sitemap Generator – If you have difficulty getting deep pages indexed or you have dynamic URLs that cause spidering problems, generate a XML sitemap effortlessly with this online tool for better Google spidering. This should not be a substitute for better site design though.
Combo Tools:
Comprehensive Search Tools – PageRank, Outbound Links (checks outbound links of a website and generates a Pagerank report for them), Web Site Traffic (monitor and display data such as Alexa, Google Pagerank and visitor traffic for a batch of domains), Link Popularity (checks how many pages indexed and how many back links to your site on search engine of Google, Yahoo, Msn, AllTheWeb, Altavista, and Sympatico), Search Engine Extractor (extracts first 100 sites in Google), Link Rank (check the PageRank and Alexa ranking of a whole list of related sites by keyword), Related Keywords, Keyword Research (select and research keyword to find how many searches for your keywords occur)