BlogBooker is a free site that turns your blog into a PDF book from all the blog's entries and comments. It works with WordPress, LiveJournal and Blogger blogs.
It is very simple. You export your blog (slightly different process for each blog service - BlogBooker has instructions for you) and then upload it to BlogBooker. It then assembles everything into a high-quality PDF file. This can take a few minutes or longer depending on the size of your blog.
This is a great way to print your BlogBook or make an archive/backup of the blog. It could also be useful for students and educators as a way to save a blog as a portfolio item.