Eli Pariser: Beware online "filter bubbles", TEDtalksDirector, May 2, 2011: As web companies strive to tailor their services (including news and search results) to our personal tastes, there's a dangerous unintended consequence: We get trapped in a "filter bubble" and don't get exposed to information that could challenge or broaden our worldview. Eli Pariser argues powerfully that this will ultimately prove to be bad for us and bad for democracy.
Similarly, you don't want Twitter to replace your RSS reader - always get to the original source. When you see a medical news item on Reuters or WebMD, don't stop there - always go to the original journal article. More often that not you will find that the results reported in the original article are a quite a bit more nuanced and less certain than the layman language, SEO-optimized headline that you first encountered. Always go to the source. If you write a blog, always link to the source.
The circle of online information (full version) (click to enlarge).