I recently picked up this guide for some friends coming to Berlin with their kids and got myself an extra copy. Whilst the book is aimed at older children, I personally found it a really useful read as it offers an unusual take on the city, and being a child at heart it appealed to me.
Half of the book is taken up with lots of interesting historical and architectural facts about the city and the second part offers a number of fascinating walking tours aimed at families but I have to say they would appeal to all ages.
The book is definitely aimed at older children but a worthy addition to any expat's bookshelf. I am looking forward to taking some of the walking tours with my son.