I ordered this drink several times this summer: Eisschokolade, and it was delicious. I saw it at cafes, restaurants, and I even drank one at the bookstore, Thalia!
It's basically a creamy, chocolaty milky drink, served with a scoop or two of ice cream in it with Schlagsahne (whipped cream, but not the hyper sweet American kind; this kind is so much better in this drink!) and a possible wafer/cookie on top.
It's really refreshing during the hot weather. To me, it pretty much tastes like what German hot chocolate would taste like if it were chilled.
The next drink I want to try is neu wein (new wine). It appears that it's the season for it now.