One of my favourite things is to take Theodore to the local sci-fi bookstore. It's filled to the brim with toys, t-shirts, board games... and yeah, books. I love to hear him walk around and sqee with excitement (like mother like son):
"Darth Maul! Look, mommy, Robots! Harry Potter! I want this Ironman! A Storm Trooper! Who's this dragon? Can I have this book about space? It has stickers!"
And of course we have to ride the TARDIS every time (or the lift, as it is).
And yes I bought him the book about space. And yes it was because I also wanted it.