What the blog for?!

The question was recently put to me, "Why blog?"
I'm not sure I know the answer. My first blog was a class assignment, not something to inspire true creativity and genuine motivation (not for me, at least). My second blog, the beginning of this blog, was simply a way to post some pictures instead of trying to email them to the appropriate people. And then the narrative that was added was for a similar purpose. Perhaps it's for time expediency, perhaps just because I'm lazy.
The laziness factor does make sense now that I think about it. Some of the entries tend to be quite personal. I don't have a journal that I write in regularly - something for which I've been seriously admonished (Newlin =) And yet, through this forum, I can write freely, almost as if to myself, but with the knowledge that those I care about and those who care about me (if you're reading this and you don't fall into one of those two categories, go check your email) are reading it as well. I'm not sure if it's a cathartic thing, a venting thing, or a passive-aggresive way to get sympathy! Regardless, I keep doing it and when I don't, people get irritated.