Question regarding fetching content.

[Rosenthal]

Hello,
I think I am going to try developing and app in which I will need to use content from another sites and what I want to know is this: For example Flipboard use twitter most of the time to fetch content and usually succeeds into bringing a decent sized summary for the article that will be displayed if it's clicked alingside with a thumbnail used in it. Using twitter is probably the easiest way to fetch content and can be customized for a lot of sources that offer this twitter stream that is almost identical to the RSS. I want to know if there is better, but with similar difficulty method, for example RSS. Using API will be difficult to adjust for every site I want to offer and will take big effort and time. But using twitter will only give thumbnail and a brief summary best case scenario. IS there any way to access comment section or if behind the link there is a gallery of images to show multiple ones from it but w/o API and before visiting the web page itself?