Instead of making some sort of judgement call (this is biased in X manner), how about a tool along the lines of something I read about in an SF story a long time ago (sorry, don't recall the title or author). I remember the point-of-view character looking at news items on a screen and things like "connotation indices" and "hyperbole metrics" were included. Those sorts of indicators would give each reader a chance to realize to what degree bias exists and leave it to them to decide how important that was.

Wow, what an interesting thing to stumble across. I happen to work for the Polar Geospatial Center and deal with satellite imagery and map-making for both poles all the time. In fact, several of our staff are in the process of deploying to McMurdo where they support the US mission with maps and other GIS related activities. One staffer, Brad Herried, shot most of the Google Streetview material from Antarctica. Nice to see it's appreciated!