The fine folks at NewsIsFree are offering treemap based visualizations of news headlines. The News Maps are restricted to a few categories, but I can see how per user News Maps could be useful.
The caveat is that this particular implementation needs quite a bit of usability work. The tool tip style of navigation nukes way too much of the map context. Something subtler and in place needs to happen. Following an article completely blows away all context you had, either by opening a new window or new tab. There's a lot of small fragments whose potential is hard to guage. A lot of the navigation is menu based where the menu winds up taking a lot of screen real estate.
This of course is based on my in-depth, extensive, one minute evaluation. There may indeed be other usage patterns that are more important.
All in all a noble effort though. Hopefully they'll get a large user population and improve the interface. The ranking algorithm they use takes into account some interesting data, including how many people click through on a story.