Is StackExchange.com Addiction Dangerous? I recently looked at the meta.math.stackexchange.com and found the second anniversary was celebrated. As in the last year's Happy-Birthday post (linked therein) , some people declared the addiction to the site.

My question is: What kind of addiction is this?

Certainly some kind of internet addiction, combined with a good portion of gamification, represented by reputation, badges, ...
But in this case, I think there is also some kind of altruistic helper-syndrome. 

Does this make math addiction a good one? Are there examples of helpful, let's say in a social sense, addictions?
For something to be considered a mental disorder worthy of it's own definition,  it needs to have some really strong effects that are consistently different from others definitions and are not explained by co-morbidity of others.

ADHD, OCD, and Tourettes all exhibit co-morbidity and common brain regions, but since the symptoms and treatment differ so radically, we treat them as distinct from each other.

In short, you are asking the wrong question : )  I'm sure there is plenty of good lit out there on helping people to the point of harming oneself.  Usually, however, this type of "addiction" is a better understood as a generalized form of something else and you would be hard pressed to come up with symptoms and treatments that would generalize only to help addicts of sites like stack exchange.

It's like talking about "breast cancer" instead of categorizing it according to cell types, treatment, etc.  Sure, you will get more money for breast cancer than a-morphic-sciency-sounding cancer, but that doesn't help one predict what could kill it.