We have the makings of a blog, although we are far from taking full advantage of it. We provide reference service via Yahoo IM (but don't specifically promote our IM name). We're working on developing podcasts and a new books rss feed. When it comes to social software websites like flickr and MySpace, we offer workshops, but have yet to create and use a Library account. Thus far, we've kept much of this "in-house," by trying to grow our own website to display photographs and encourage interactivity.
See, we're trying.
But now I'm trying something new. Rather than just the Library using 2.0 technologies, I've created a Tech Tools webpage to encourage patrons to use some of these tools to improve the way they use the library - hence, Patron 2.0.
This is just the first pass, so please let me know of any tools I've missed, so this list can grow.