Far and away, the leader in that field is SEOBook.
Aaron has moved away from this eBook model and now offers a subscription service which provides you with over one hundred training modules.
Aaron provides a lot of video tutorials, spreadsheets, and tools.
In addition, there is a private forum where you get to talk to people like Aaron and me.
It's $99/mo and it's worth it.
For free, I think NetBuilder is the best place to learn SEO.
We have a great deal of information here. I was thinking again this morning about how to organize it to maximize usability. I think that in six to twelve months, that's going to become a major concern for us.