During the 2008 election I saw several filters available - Firefox plugins, special news searches, etc - that would hide links and stories from sites on the other side of the political spectrum. That's as clear cut example of a filter bubble that I can think of.
As I write this, I realize that I live in my own online filter bubble. I visit the same sites on a regular basis and don't venture out much except when following links from sites like HN. It is a filter, but it's self imposed. Instead of wasting a lot of time online, I gravitate toward communities that do the filtering for me. It may be a bubble, but the alternative would lead to wasting even more time online.
As I write this, I realize that I live in my own online filter bubble. I visit the same sites on a regular basis and don't venture out much except when following links from sites like HN. It is a filter, but it's self imposed. Instead of wasting a lot of time online, I gravitate toward communities that do the filtering for me. It may be a bubble, but the alternative would lead to wasting even more time online.