It was Dad's old set of Richards' Encyclopedias (complete with a monstrous squashed butterfly -- why?) that first taught me to value children's encyclopedias. They're a window into a world and world view long gone, an idealised world in many ways.
But they have fantastically clear and simple introductory explanations on a great many things that don't go out of date and best of all, they have stunning black and white photos. I have limited to non-existent artistic talent, but I enjoy drawing based on these old black and white images -- not that I've done so for ages.
A few years back I picked up an entire set co-edited by Enid Blyton. Sweet.
It makes me wonder how in 40 or 50 years time people will try to look back on today's kids' entertainment. How will they check into 2011's internet world?