You can find children's book on children's corner.
There is a wonderful library in my home town with helpful staff and a great selection of books on all topics - I often use it for browsing, looking up information not available online and simply as a place to relax in the quiet and enjoy a good read with a coffee - Libraries are important for children and my favourite often organizes activities to get kids interested in reading and in the other facilities it offers :)
Libraries are very important for children. It's great to encourage reading at a young age instead of shoving electronics at them to get them out of the way. Too many kids have vocabularies that are horrifyingly miniscule because parents no longer promote reading.
Personally, I just buy the books..I don't like the idea of renting them. For smaller kids, I think it's a good idea.