One time, over lunch, I and an officemate were talking about Facebook. She has an account but recently decided to abandon it for personal reasons, and told me that it's better for her to just maintain one personal site (another networking site, not FS though).
In my case, I have plenty of personal sites but maintained a few. I have a Friendster (w/c I left abandoned since early this year, and been long considering it for obliteration), Multiply (more of storage for personal photos shared with friends), Flickr (for my 'ambitious' photography portfolio and a few what nots), DeviantArt (for my artwork churvah). Twitter, and this blog in Blogspot. The recent addition to my so-called 'internet properties' was Facebook (July, last year).
My officemate thinks that having these sites is like revealing your life to the world. True -- but I assured her that my networking sites are set in 'private' (Blogspot, Flickr and DeviantArt are left open for public viewing). I am fully aware that maintaining a blog can be risky -- but as long as I'm not stepping others' toes, I'll do fine. I even have it linked to my FB because I chose to. It's not like I'm forcing people to read it -- for it's purely voluntary. They can ignore it if they want or even remove it. *defensive*
Seriously, I really don't have to justify this predilection of mine. To each his/her own, I guess. I enjoy writing irrespective of what others think of my posts or the mistakes I have with grammar (w/c I think it's not really that bad). I like sharing my random thoughts and moments to a faceless audience or to online buddies I met in the blogosphere. I like it more that recalling old good (and bad) memories is just a click away.
No need to justify further. It's my life, anyway.
P.S. I have yet to watch HP & the Half-Blood Prince. -- This is soooo not acceptable for an HP fanatic.