This is the only series of books my kid read yet. It was in the non-fiction under math in the children's section of the library.
http://www.mathmonsters.com/Here's what the stories are like.
http://vimeo.com/m/19052615They're friendly, interesting, not complex, can be read in about an hour.
My kid liked the Junie B Jones book on tapes but he burnt out on her. The librarian suggested Horrible Harry. He can read the Boxcar Children but doesn't like it. The print is easy on the eyes in that series. Really what he's doing now is about three picture books a week from Little Golden books. He can read one or two in an hour or so. There's enough words that offer new vocabulary, old fashioned or modern sentence types, a variety of stories, and great pictures.
Don't forget to order toy catalogs. Don't you remember looking at the Sears Catalog. Anyway, if a kid don't like the same series styles of books as we read about go look in the children's non-fiction section see whatcha find there.
He does read a ton of Garfield and Peanuts (Peanuts is having a slightly weird influence at this point, I think!)