If you NEED ice cream and you're in Prague city centre - you cannot do better than Cafe Angelato. Incredibly good value also, considering location (between Wenceslas and Astronomical clock)
I had a 4 scoop pot. It cast just 100czk (trust me - for this quality, it's CHEAP!)
All delicious and amazingly, despite the fact I ordered in the carefree style of a 5 year old, they all worked very nicely together... this gave me a new idea for making the grueling job of ice-cream testing less 'arduous' :P