After trying all of the sites suggested on the 23 things page, I decided to set up a Mixx account. Mixx was very easy to navigate and the initial page of offerings seemed closer to my interests than some of the others listed. Adding a link to a story was very simple. I thought it was interesting that all 4 sites had several of the same articles about the presidential race tagged on their start page -- evidently, it doesn't matter with major news which site you choose to favor, the same source articles will show up.
I'm not sure how I would use this professionally in a library. It is another source to sort through the amazing amount of information that's available on the web (always a plus); however, if I was looking for some specific information, I don't think it would be a site I would use unless several others lacked information.