My very favorite book for exploring and sharing nature with kids is This Book Was a Tree: Ideas, Adventures, and Inspiration for Rediscovering the Natural World by Marcie Chambers Cuff. Its both a hands-on book of crafts and activities and a book of principles and ideas for reconnecting with the natural world.
Brown Bear, Brown Bear, What Do You See? I see a book plagued by lack of conviction, critical thinking, and true intellectual curiosity. It's doomed from page two.
These super handy apps can make anyone an adventurer. They also make a decent case for swapping Angry Birds for the real thing. Like geese. (Although, geese are always angry.)