I really liked looking at the different wikis. I especially appreciated that wikis can use different formats, like the one for November's CSLA conference. For me, the conference ones are especially invaluable, since it's hard for me to get out to many of these. If a lot of folks contribute and the presenters attach their handouts and links, it can be almost as good as being there. Well, not really, but it'll have to do. I absolutely loved the BookLoversWiki and was considering doing something like this for readers advisory at my high school. But then I decided that a blog was a better way to go.
Here is my addition to the 23 Things Wiki:
I love using YouTube for fun. I was looking at some Vienna Teng videos, which led to the Wellesley Widow videos, which let to the fact that the Widows (an acapella group) played at Clinton's inaugural parade. WTG Wellesley women!
I think this could be useful for libraries, but only if we as professionals hone our video skills.