While working on a project I found a really cool site by St. Louis County Library: Teen Zone Book Reviews. It is a list of books that have been reviewed by kids ages 12-18. I was impressed by the thought that went into each of the entries. This could be really useful for a Juvenile Literature Librarian, particularly if SLCL ever added an RSS feed for the page.
The principle is transferable to any library Web 2.0 OPAC though. Why not have a link to the most recent reviews on the main library page? Why not have a link to the most recent reviews by Biology students (in an acdemic library), seniors (in a Public Library), or 10th graders (in a school library)? Filtering by user-volunteered information like age, major, or class year and then providing RSS could really open up the library community in new ways.