There are many tools available. For example to measure where or how your site is listed in search engines, or what your link popularity is (who links to you). Like which pages are indexed in Google and many more. It is self-evident that those tools are part of your (continuing) SEO-plan. Many tools are free available. Here you will find a selection of free tools, just try them out.
Wouldn’t you be real happy if you would have one tool that checks your rank, gives you all SEO information about your site (or your competitor’s) has the best keyword research tools across the web, has competitive research tools, being able to compare up to 5 competing sites against each other, has easy data export and a lot of other features all in one handy Firefox extension.
Discover what keywords you should be targeting.
fast & easy to use
clean data from Wordtracker
easy data export
See important competitive research and search engine marketing data directly inside Google and Yahoo search results.
Want to know where your website ranks in the search results? SEO book’s Firefox Rank Checker extension allows you to easily check your website rankings in Google (US and international), Yahoo, and Microsoft Live search.
Class C Checker
This free Class C Checker tool allows you to check if some sites are hosted on the same Class C IP Range.
This Class C Checker may be used in these cases:
You own several cross-linked sites:
it may be more efficient (for SEO purposes) to host them on different Class C IP ranges (this is only an advice, not a must do)
You’re going to get new links from different sites
check if they share the same class C IP range
Google Webmaster Central
Statistics, diagnostics and management of Google’s indexing of your website, including Sitemap submission and reporting.
“The Search Tool with Complete Page Analysis for each Result”
Server header check
Check your server to make sure the proper HTTP Status Codes (200, 301, 302, 304, 307, 404, 410) are being returned in the server headers
Google advanced search operators
Google supports several advanced operators, which are query words that have special meaning to Google. Typically these operators modify the search in some way, or even tell Google to do a totally different type of search
Comprehensive Guide to .htaccess
Though not a “tool” per se, this comprehensive tutorial about how to use the .htaccess file is excellent.