In any museum in Amsterdam, for 59,90€ you buy a Museumkaart, which gives you free access to 400 museums in the Netherlands. Valid for 1 year.
My favs:
Here you’ll find the list of museums with free entrance with the Museumkaart.
FOAM, a jewel specialised in photography.
Eye, the filmmuseum in an upcoing area in the city. Take the boat just behind central station to get there.
Het Stedelijk Museum, another must see.
Museum Van Loon, a beautiful house where the happy few organise their weddings 😉
Tropenmuseum, nice exhibitions.