Rainbow Magic Series by Daisy Meadows http://www.rainbowmagic.co.uk/
Geronimo Stilton http://www.scholastic.com/titles/geronimostilton/haveyouseen.htm
My Weird School by Dan Gutman http://www.dangutman.com/pages/books.html
Magic Tree House http://www.randomhouse.com/kids/magictreehouse/
The Black Lagoon Series http://www.mikethaler.com/biography.htm