I have always been curious to find out more about websites, keywords, backlinks, page rank and their correlations with crawlers and search engines. Every time I heard about a tool that promised to unveil an optimization secret, I went ahead and tested it.

There was a time I made plans about discovering or creating the ultimate magic SEO wand. Fortunately, I woke up one day and realized that magic wands exist exclusively in fairy tales for good reasons, but the online world gives enough alternatives that can help me understand, analyze and improve a website's relationship with Google.

So here is a list of 10 free SEO-tools that proved useful and helped me answer some of my optimization related questions.

1. Google Adwords Keyword Tool
It helps you find keyword ideas along with monthly local & global searches.

2. Search Based Keyword Tool
Another Google tool that provides keyword ideas, based on actual search queries, matched to specific pages of your website with your ad and search share.

3. Google Datacenter Page Rank Checker
Fill in your site’s URL and hit enter. The query will return PageRank values from various Google datacenters.

4. Visual PageRank Overlay
This tool shows you all links of a website and the corresponding PageRanks of the linked pages.

5. Keyword Density Checker
Provides the percentage of occurrence of the keywords you use. I stopped using this some time ago, as a friend developed a custom keyword checker for me. I did test it earlier today and it's still rocking.

6. Advanced Google searches
A useful resource for search engine optimization (for keyword research & different types of analysis) among other things.

7. SEOpen Firefox addon
Provides quick access to web-based tools to help with search engine optimization. Quickly checks inbound links, PageRank, http headers, and much more. I've been using this one a lot, as I'm a Firefox fan and SEOpen is reliable and always at hand.

8. Google Banned Checker
This tool will analyze your domain with Google search to detect if the domain is banned.

9. Link Popularity Checker
Link popularity check is a great way to measure your website's online awareness and overall visibility. Simply put, link popularity refers to the total number of links or "votes" that a search engine has found for your website.

10. Link Vendor Link value & price calculator
Provides an estimate price for link ads. Although it gave me some errors today, it used to work okay. Hoping it's a temporary problem, I decided to include it here, too.

Some of the links above are from websites that offer related free tools, too. You may want to do your very own digging for other practical ones. Speaking of which, do you use any SEO related tool?

On November 9, two new locations will be added to the Pingdom monitoring network:

New York

Chicago

This brings the number of Pingdom monitoring locations to 15, of which 10 are in North America and 5 in Europe.