Is there a API or systematic way of stripping irrelevant parts of a web page while scraping it via Python? For instance, take this very page -- the only important part is the question and the answers, not the side bar column, header, etc. One can guess things like that, but is there any smart way of doing it?
One approach is to compare the structure of multiple webpages that share the same template. In this case you would compare multiple SO questions. Then you can determine which content is static (useless) or dynamic (useful). 
This field is known as wrapper induction. Unfortunately it is harder than it sounds!
Stripping irrelevant parts of a web page