Lots of shops all around, selling lots of stuff. Unique to Prague?

Check out the Museum of Communism, interesting exhibits and some neat stuff in lobby gift shop. I should have picked up some original communist-era posters. Just off Wenceslas Square. http://www.muzeumkomunismu.cz/eng_map.html

Also, the Alphonse Mucha museum. Significant creator of Art Nouveau commercial artwork. Did posters for Sarah Bernhardt, and the still-used JOB cigarette paper artwork. Nice giftshop with a variety of posters and other items. Also near Wenceslas Square. http://www.mucha.cz/index.phtml?S=addr&Lang=EN&NoB=1

Finally, depending on personal proclivities, you can pick up some Absinthe. There are a number of Czech brands purporting to be true to the original recipe. Hill's comes to mind. Haven't tried the stuff myself.

Make sure and take the time to sit in an outdoor cafe and watch the world walk by. Old Town Square is nice. The beer is very, very good. Not your father's Budweiser though.