This site, produced by Scholastic, is a nice tool to use in helping teachers to select books.  It includes leveled searches based on the “Level System” your school uses.  Another nifty feature is the “Book Alike” search, which allows you to look for books which are similar to certain ones the student already likes.  For the latter, the teacher can even use a toggle switch to indicate whether to search for books at an easier, harder, or equivalent level to the book cited.  A Book Wizard widget can be added to your website or blog for students and parents to utilize as well.