The Pet Sitter series by Julie Sykes is one of my recent acquisitions from the Picnic Basket. These books fall into the beginning chapter book reader category that Magic Tree House or Junie B. Jones also fall into. These books have a bigger font and more pictures than either Magic Tree House or Junie B., making them even more readable by those just starting out with chapter books.
The premise of the first two books is that Max has been hired as a pet sitter for some very interesting animals. There is a bit of magic in these books that I think kids will enjoy. As with most series book of this level, there is not much character development. For me as an adult, I can't say I enjoy these types of books a great deal, but I can definitely see my early chapter book readers enjoying them a lot.