6 yr ds is reading a lot of different things right now. He just finished the Spiderwick Chronicles (all 5 books read in less than 3 days). He is also working through The Lost Years of Merlin (1st book), Dragon's Eye, Harry Potter's 5th book, the Invisible Man (Great Ill. Classics), and several others (I can't keep up with him!).
9 yr ds is re-reading Harry Potter series (currently in book 6), reading Redwall, the newest Spiderwick Chronicles book, and lots of Calvin and Hobbes.