I used to have something on a website similar to those, about 5 or 6 years ago. It is where i posted fictional stories and poems that I wrote, because I knew that no one would really give a crap about my life enough to read about it. Anyway, I found it sad that no one seemed to realize that it was fiction. I got many responses such as "your friends sound so cool, I wish I knew how to teleport!"
Eventually, there was one annoying posting trend that happened there, after about a month of being on the site. People spammed my page with advertisements to read an anti-suicide chain letter. So, I wrote a pro-suicide chain letter that was a parody of theirs, and spammed every single person who spammed my page with it. I received approximately 50 pieces of hate mail in one day, just from the pro-suicide letter. And many more general messages such as "you are one disturbed individual."
I might join myspace, because my boyfriend has one himself. But right now, I don't see much of a point because the layout of the site is terrible for what I'd want to do with it.