I finally had a bit of time to compile this livebinder of free eBooks for primary school kids. It includes fiction, non-fiction, audio books, plays, create your own stories and eBook research I was able to build on suggestions from the NZ library listserv, which is a wonderful resource for librarians.
Some public libraries also allow you to borrow eBooks or use eBook sites they have subscribed to. Hamilton City Libraries, for example, allows you to access Tumblebooks, an interactive eBook site. They also lend out eBooks, including some picture books and fiction for children.
If you know of any more sites I would love to hear about them.