One souvenir that you'll see commonly at German Christmas Markets are these little ceramic, clay, or porcelain houses. (Although now you'll see all types of buildings including churches to castles.) Mine are from Kastel Keramik Haus (or they are also known as Lichthauser) and I purchased it at my first Christmas Market in Frankfurt. It was the last night of their market, and so I got some of these little houses for 50% off. They either have a hole in a the back, or separate into two pieces so you can place a candle within it. You'll see the light flickering