In summary:
iGoogle page - still using this for combination of links to my RSS feeds, and the 'Days Since' and 'To Do list' widgets, but I haven't set it as my homepage.
Blog - still hoping to keep this up, though I'm considering moving to a different host.
RSS feeds - this has been one of the main highlight and benefits of the 23 Things programme for me; these certainly help me keep up to date on various interests.iGoogle page - still using this for combination of links to my RSS feeds, and the 'Days Since' and 'To Do list' widgets, but I haven't set it as my homepage.
Blog - still hoping to keep this up, though I'm considering moving to a different host.
Flickr & Picnik - I'm not a big photographer, and I don't really want to share my efforts with the world. When I do want to share pictures, I put them on Facebook, or email them, or possibly even have them printed out and pass them around, although that feels slightly like blasphemy amongst the Web 2.0ers...
Delicious - I feel that I missed the point on this one. It was useful to mine the lists of a couple of people/places, but I won't be using it in a regular or dynamic way.
Podcasts - ho hum. I found a few intersting ones, and it was good to be given a bit of nudge towards finding and listening to some, but I can't say I found anything professionally useful.
Facebook - I've used it for ages, not sure about its usefulness or libraries (see my humble opinions at greater length below)
LinkedIn - Can't believe that anyone has ever made contacts which were both new and useful on this clunky site, and even less found a job.
Twitter - Fun for a while, but the novelty soon wore off.
Wikis - Useful within online communities, Wikipedia to be used with caution...
Office 2.0 - Could be very useful between colleagues.
Widgets - Handy and fun!
I noticed whilst writing this, that I've said almost nothing about libraries. I've learned a great deal about Web 2.0 for myself, and have definitely acquired new skills. I don't think many of them could be productively applied in my library, which caters mainly for academics and researchers visiting once only, but I'll bear them in mind for when I get a permanent position...though by then I expect a couple of these Things will have fallen by the wayside, and a few more arisen...