Thing 7 was all about Twitter. I have used twitter for well over a year now but never on a more professional or serious basis. After I signed up I found out that only few of my friends actually use twitter and that none of my fellow students have a twitter account. Their lives are all on facebook. A few months ago I read about a study which found out that twitter gets used by 'older' people (i.e. those in their late 30s and older) and not really by the current student generation. Therefore, I always considered a library twitter account somewhat useless if it is aimed at students. I think that twitter is more useful for spreading links and news to other librarians. Given that so many Cambridge librarians signed up on twitter and connect to each other, makes twitter quite a powerful network - if people keep using it after the novelty character (or 23 Things workshop, whichever happens first) wears off. Here's a screenshot with some of the library 'tweeple' I'm connected to now:
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As for tagging, it reminds me of the Library of Congress entries I use when cataloguing books: You just have to get it right, otherwise your entry won't be found and will be lost forever (slightly exaggerated, but you get my point). However, I would argue that it's more about the quality of tags rather than the quantity. Therefore, I won't add more tags to my blog but rather review the existing ones and substitute them by more suitable ones where necessary.