How about a section of the site devoted to reviews of Perl books (could be extended to other forms of info).
Reviews/comments could be posted as normal and votes could be used to give an overall rating for the book. Perhaps the books could be broken down into newbie and experienced categorys so people could find a decent book that is written at the right level for them.
You could even get comments from the authors. I'm sure merlyn would have something to say :-)