ClickTale
Find out what visitors are doing on your site. Discover how visitors interact with your online forms; what they type, how long they take to do it, which fields they skip, and why they leave.

Google Analytics
Google Analytics provides powerful insights into your website traffic. Learn more about where your visitors come from and how they navigate your website.

Google Webmaster Tools
Google Webmaster Tools provides you with detailed reports about your web pages’ visibility on Google.  Just add and verify your website and you’ll see information immediately.

Linkscape
Linkscape provides link data across 240 million domains. With this tool you can identify how many unique domains are linking to a webpage, sub domain, or to your entire website, analyze your competitors’ websites to see what they’re doing right and how you can imitate what they’re doing, determine the quality of potential links to your website, find specific link achievement targets and measure the success of viral marketing efforts.

X-ray
With this tool, you can see how the on page optimization of any page looks, keyword density of the page, popular phrases on the page, how many links point to a page, how many links point from a page and more.

Xenu
Helps you find broken links on your site.

Yahoo Site Explorer
Site Explorer allows you to explore all the web pages indexed by Yahoo. You can view the most popular pages from any website, review a comprehensive site map, and find pages that link to that site or any page on the web.