One thing I would like to recommend first to everyone in the 23 things class is that they add a subscription to RSS on their blogs. Once you do the RSS assignment you will see how important it is to make it easier for others to follow your blog. I, of course, am getting lazy to actually visit your blogs and want them on my reader :)
Also you can sign up for an RSS feed to your own blog's comments in Google Reader. That way you can monitor if your blog has received a comment without actually going there.
I have created my first wiki: Cool Crete. It is a place that lists links of interesting websites about concrete. I am not totally obsessed with concrete, but it was the easiest thing I could think of to quickly build a wiki.
Wetpaint was easy to use and get started. Since I do not really want to maintain this site I did not use all of its features. But it has a really nice setup for evaluating your wiki as far as helping you get traffic on it. You can e-mail all of your friends and it helps with setting up titles, tags, and headings for search engines.
I did not mess with the picture part of it too much because they had to be formatted smaller than my images I have conveniently on hand. I would like to be able to add my own background to the template to make it more interesting.
The basic posting of starting a thread was very easy and I think students would be able to use a wiki well. The future use that I am thinking about using wikis for would be a site dedicated to my WebPals project. It could be a place to invite classes to participate, explain how to participate, and discuss problems/solutions.
Overall, my feeling right now is that I like blogs better than wikis. Maybe because I want to control content. It seems like anything in a wiki could also be in a blog with a discussion in the comments, but perhaps the discussion nature of wikis encourages people to be involved with them.