If you're in need a few witchy ghosty books check out these:
Monster Mash: Awesome illustrations join this fun song.
Witch Way to Witch School: Magic combined with school. This one resembles Madeline.
Monster's Monster: A cute story about three monsters who hope to create the biggest baddest monster, but...things don't work out just right.
Witches: A childhood favorite
Wait til Helen Comes: Another childhood favorite - creepy!
Dying to Meet You: Humorous fun ghostly tale
Dial-a-Ghost: More fun than scary, but there are some gruesome bits!
Ghost Huntress: Spooky series about one girl coming to terms with her abilities. She starts ghost hunting with her friends.
Salem Witch Tryouts: Not spooky - but tons of fun. Cheerleading with Magic and trying to fit into a world where magic rules and you don't!
Mediator series: One girl can see ghosts - most of the time she helps them or kicks their butts to make them cross over - except for that one dreamy boy.
Bras and Broomsticks: Imagine your sister getting witch powers while it passes you by!
Sweep series: This is ONE of my favorite witch series - lots of danger, action, and romance.