There are a couple of tourist passes in Krakow (also known as sight seeing passes), including Krakow Card, but we do not recommend them. Kraków is a very cheap city.
The Krakow Card does give free entry to a lot of attractions (including Oscar Schindler’s Factory, St. Mary's Church, Rynek Underground, the Cloth Hall (Sukiennice), Old Synagogue and more), so if you are intending on visiting a lot of those you should go to their websites and work out if it will save you anything.
It also includes free public transport, but if you are staying in the city center you probably won't get any busses or trams. If you do, it costs 2.80zł for most (under 20 minute) trips. It does include transport to/from Krakow Airport (most tourists get taxis, see our Krakow Airport guide for details. A bus from old town is only 4zł each way, anyway). Additionally it includes transport to the Wieliczka salt mine, but most tourists book a tour from a tour company that will pick you up from your hotel anyway.
But of course depending on what you will get upto in Kraków it might save you a lot of money. They do have a lot of attractions, so it could work out for you!
Read about exploring the abandoned Liban Quarry (and ex Nazi labour work camp)