The I amsterdam city card is your key to a visit to Amsterdam. This card provides one to three days of unlimited travel with GVB tram, (night) bus, and metro routes (but not with Connexxion, Arriva, or national train) in Amsterdam, free entry to 37 museums and a canal trip. And, you also get a 25% discount on many attractions and restaurants with the I amsterdam city card.

Fares for 2013:
I amsterdam Card 24 hours (1 day)     € 42.00
I amsterdam Card 48 hours (2 days) € 52.00
I amsterdam Card 72 hours (3 days) € 62.00

Available at GVB Tickets & Info and the VVV Amsterdam Tourist Board at Stationsplein. 
For more information, go to IAmsterdam.com