I remember learning about the psychological factors of addiction in my college psychology class. The main theme seemed to be random rewards. If you made the reward equal to the amount of work that needed to be done mice would just click the lever until the got the reward, it was easy, predictable , and generated predictable behavioral patterns.
If you made the reward random, such as sometimes the mouse would get the reward quickly after a number of clicks or even instantly. Then sometimes it would take for ever to get the reward. Your random reward pattern would generate truly addictive behavior.
Blogs exhibit a random reward pattern, both for readers and writers who don't receive very many comments (but every once and awhile do).
Thought I would share, so if you notice the number of blogs you are reading going up then you might notice that you are also addicted.