I think if you look at the blogs that you normally read - it's usually fairly obvious why some people blog - in the case of fatcyclist, it gave him a huge support group, was probably cathartic getting those feelings out there, and look how much good he's accomplished for various charities along the way - and he's managed to be given a few sweet bikes while he was at it.

I don't have a blog because I have nothing to say, and I'm pretty lazy. However, I've noticed I have a ton of things to say on facebook, and my friends seem to find me amusing enough, or they just pretend to do so. I've been toying with the idea of one a bit more lately because there's some business type endeavors I'd love to be able to tie into a blog.