One of the things you MUST do is visit the Wielieczka (sp?) Salt Mines!!!!!
The place is amazing - we were stunned at what they've got hidden there underground (including a whole cathedral that's carved out of the salt). We were staying at the Ibis Hotel in the centre of Krakow (in November this year), and booked an organised tour that picked us up from the hotel and took us to the mine. If you're on a budget, it's probably better to take a local bus than to book a tour. We found that it would have been cheaper, but less convenient to do things that way.
We resisted the urge to visit the concentration camp (is it Auschwitz??) - we just didn't feel the need to put ourselves through that kind of ordeal whilst on holiday, but if that's what you're interested in, you'll find it's just outside Krakow.
The city has a nice castle that's worth a look around, and a stunning cathedral. It's one of those cities where you just need to stroll and see what you discover. And look out for the stories about the pigeons in the town square, and see if you can find out why the trumpeter who plays on the hour pauses in the middle of his tune!
Krakow is a nice city, and VERY cheap too - enjoy!
[Edited 2005-12-14 22:07:41]
Ladies & gentlemen this is Captain Tobias Wilcock welcoming you aboard Coconut Airways flight 372 to Bridgetown Barb