Amazon is fantastic, basically everyone in the industry that I know has been going there for inspiration first forever. Recently, Facebook has taken that place, and Google to some degree (although Google's case is a very specific one).

Wow, thats amazing. Its the last place I'd look for inspiration these days. Perhaps 8 years ago. It just doesnt make sense to regurgitate things that could be done better.

I find the whole UX clunky, especially the checkout process. Its trying to be too many things to too many people and have solved some hard issues - just not very well.