I came across [1] some weeks ago, which (although didn't give me the flexibility to choose my topic), did fulfill my need to look at the view from both sides on, presumably, the hottest topic of the day.
They have a "curation"-method to selecting the articles to show. I am curious as to if this extension uses pre-selected websites (e.g. WSJ will always show the Right-leaning view), or is there something smarter than that