Open communication makes us better journalists. It's always been the case with newspapers that when you print a story, readers will call or write you with feedback, and sometimes with additional information that you didn't know about at the time you published the story. Sometimes this leads to good followup stories. E-mail enhances that. First off, we usually refer to sites that are recommended by groups that have outstanding credibility.
Fresh information can be a very important indicator of credibility, too.
Realize when you're going to a site that belongs to an advocacy group. A lot of sites do have an agenda, but that agenda may not always be readily apparent. I think that in the long run, those online news and information outlets that are credible will survive. Those that aren't credible either won't survive, or they will become know for what they are. It's like back at the turn of the century, when yellow journalism was on the rise and a dozen or more newspapers competed in each of the major cities.