afx: Good German breweries include Warsteiner (sort of like the Anheuser-Busch of Germany), Kapsreiter, Spaten, Schneider and Hummel-Brau. They range from good to great, and you can find all sorts of different regional brews and seasonal brews.
I’m sure you’re familiar with the lagers and pilsners and bocks, but you might also try Kolsch (lighter and fruitier pale ale), Gose (spiced amber), Berliner Weisse (which is the city’s signature beer) and Rauchbier (smoked malt). Gose and Rauchbier are making a comeback and well worth a try (if you can find them).
Being of German extraction, I am definitely biased, but the squareheads do make great beer (along with fine automobiles, weapons and buxom blondes named Inga).