IstanbulKart

Istanbulkart is the name of the smart card you can buy for public transport.  It's like Wellington's Snapper card, but works on buses, trains, cable cars, trams, and ferries.  Most rides cost about $1 or $2 NZ, so getting around is cheap.

You charge it up yourself at a machine.  On a related note, here is the sunset last night as seen from our windows:

Catching the tram home from Sultanahmet