On one of my first visits to Amsterdam as a child we went to Waterloo Square, and what an impression it left on me.
You could buy everything at the daily flea market. Pins and suits and sabres and boat lamps, it was like walking around in a Tintin story. It was bigger then, before the city of Amsterdam decided to ban the market in 1977 for 11 years so that it could build its monstrously ugly city hall there.
Waterloo Square (Dutch: Waterlooplein) was where the merchants from the nearby Jewish quarter were told to ply their trade from 1885 onwards. Last Saturday I visited the festivities surrounding the 130th anniversary. A lot of the stalls these days offer the same knickknacks you can get from every generic tourist shop in Amsterdam, from wooden tulips to gable shaped fridge magnets, from T-shirts with marijuana leaf print to colourful chullos. You can still find something special there if you know where to look, but politics and the likes of Lonely Planet seem to have done a number on the flea market I remember.
Update 15-6: I added 9 more photos to our Flickr page.