A good resource for any trip is the New York Times travel section, for articles under the "36 hours" theme.
On July 22, 2007, the "36 Hours Amsterdam" by Gisela Williams at page 11, laid out an excellent overview. Complete with map. This is especially good because it includes sites for real activities, not just walking and viewing. Try it. Get a bike, eat, find a bar, dance, go up the watchtower, discover pancakes, dress up, go to the factory and party and beach it.