I do basic python programming and now I want to get deep into language features. I have collected/considered the following to be advanced python capabilities and learning them now. 

Decorator
Iterator
Generator
Meta Class

Anything else to be added/considered to the above list?
First, this thread should be community wiki.
Second, iterators and generators are pretty basic Python IMHO. I agree with you on decorators and metaclasses. But I'm not a very good programmer, so I probably find this more difficult to wrap my brain around than others.
Third, I would add threading/multiprocessing to the list. That's really tricky :)
What are features considerd as advanced python?