For a lot of stuff, I'm not that into doing it collaboratively. Links, for example. I actually wrote a link application for myself a while before it became a thing because I wanted to share bookmarks between work and home and so I never felt the need to sign up to delicious (how ever it's supposed to be punctuated). Flickr is kind of fun but I'm not a compulsive photographer or consumer of photographs so I don't make much use of it. Maybe I'm just a bit of a web 2.0 philistine. It's seems to be all about getting your content via some sieve of popular opinion without interaction but I'm not so sure about that. That's kind of why I like blogs - there, when you see a link, you have a bit of context, not only from the post but from the whole blog - you know what sort of things that person is interested in, how they use those word, what it's likely to mean. I still haven't got to the point where I can reduce that understanding to a tag search.
And of course, I could use the "Blog" functionality to post this to my LJ but that would mean entering my LJ password here, which would then be stored. I wish they used OpenId. That would be kind of cool.