Spiderwick Chronicles by Tony DiTerlizzi and Holly Black
1. The Field Guide
2. The Seeing Stone
3. Lucinda's Secret
4. The Ironwood Tree
5. The Wrath of Mulgarath

Beyond the Spiderwick Chronicles by Tony DiTerlizzi and Holly Black
1. Nixie's Song

Companions to the Series:
Notebook for Fantastical Observations
A companion book that contains some descriptions of creatures in the books, but also has blank spaces and charts to create your own creatures
Arthur Spiderwick's Field Guide

See Also:
RIYL Harry Potter
RIYL Golden Compass

Resources:
Border's Live Interview with Tony DiTerlizzi and Holly Black
The Spiderwick Chronicles Movie Trailer at Borders (Also includes Games )