Favourite SEO Tool?

Hi

There are many SEO Tools out there.. what are your favorite tools?

Here's my list of them
Google Trends
Google Insights for Search (new google insight search)
Seo Book Keyword Suggestion Tool (keyword research)

So what's yours? list your tools url below for everyone to share I think this thread would be a useful post later on if everyone contribute .

Thanks

 

I'm not sure if this is a SEO tool but one of the most useful tools is:
https://adwords.google.com/select/KeywordToolExternal

 

Here are some of my favorite seo tools.

google adwords keyword tool
google analytics
seopen toolbar
search status adds on
domainpagerank.net
seocentro link popularity check tool
backlinkwatch.com
copyscape.com

 

spyfu.com/

 

Google adwords
google trends
Seoquake

 

I use statcounter to track the performance of my sites, and google adwords tool to research for keywords.
U might wanna check articlechecker.com to check duplicate contents.

 

Thanks for your replies.

 

The best two SEO tools out there are
Google's AdWords Keywords Tool and IBP 10 (for beginners)

 

IBP , Xrumer

 

For seo tools that's the best!

 

statcounter
hittail
crazyegg