What are some good Chinese short books/novels for beginners?
Here's one starting point:
我的第一本日记：二年级的美羊羊

I think it's part of a series of similar books called "我的第一本日记".
It's a schoolgirl's diary but not a real diary, I think an adult actually wrote it. It's got pinyin printed above the 汉字.

I read it myself; didn't understand everything but I still found it to be a rewarding read. Makes a nice change from all the boring textbook material. It's probably suitable for Chinese kids 8 years old or upwards.

I admit this one is probably more for intermediate students than beginners, but perhaps there are others in this series that are easier.