What SEO tools / sites do you use?

[Nathalie]

I have been out of the loop for a while and am looking for good resources to use for SEO research for PPC advertising.

I used to use Overture's keyword tool to not only find good keywords but get a good idea of the number of searches on the keywords.

This tool is no longer available.

Google's interface doesn't seem to have an easy way to estimate search traffic before adding keywords (unless I'm just missing where to do that)


The free version Wordtracker is ok (http://freekeywords.wordtracker.com)


Does anyone have a compiled list of good resources of SEO tools (both paid and free are fine, but I prefer free of course) that you use?

My bookmarks are way out of date from when I was more info this.


Looking for things like:

- keyword research
- estimate of PPC pricing on keywords and traffic
- tools to check my web site for errors / seo-unfriendliness
..etc


Thanks