I would like to know other areas besides documentation as well. Mostly, I've only found piece meal blog posts, etc regarding how to solve specific AWS issues, etc.
AWS engineering blog is good - http://aws.amazon.com/blogs/aws/
AWS forum has helped me solve issues I've run into - https://forums.aws.amazon.com/
I can sometimes see new methods for approaching things with AWS tags on StackOverflow
High Scalability occassionally covers robust architecture learnings eg: http://highscalability.com/blog/2013/11/5/10-things-you-shou...
http://highscalability.com/blog/2010/8/16/scaling-an-aws-inf...
http://highscalability.com/blog/2014/3/11/building-a-social-...