Heard of Duck Duck Go via Linux Mint 12. Although privacy issues with the Google browser or Facebook are valid, the filter bubble phenomenon is exaggerated. Granted, Google has bias in its algorithms (it is in their best interests after all) but there is an alternative (or a complement if you will) and that is Duck Duck Go search engine.
The more serious knowledge asymmetry most people encounter is that of non-awareness with respect to open source software. When all people know is Windows or Mac or iOS, I think we have better things to do to campaign free/open source software to the rest of the world.
Don’t Track Us (illustrated)