SEO Book
 

http://www.seobook.com

Aaron Wall's seo blog and toos. Lots of info his tools are free and top notch!

I use the Keyword tool tells you how many hits any keyword, including adult gets each day across the major SE's
http://tools.seobook.com

I would recomind anybody just learning about SEO or trying to get your websites to rank to read through his stuff.