Can't drink domestic p*sswater anymore, ever since I spent time in Germany in the latter days of the Cold War and got used to German beer. Well... with the probable exception of probably Sam Adams, Shiner Bock and some microbrews.
Partial to the local brew of Bitburg and Spangdahlem air bases -- Bitburger Premium Pils. They've been brewing only one kind of beer since 1817, and that's their famous pilsener (though they now have a light and a non-alcoholic version as well).
Some other German beers worth checking out:
Warsteiner - Bitburger's competition, not as 'hoppy' as Bitburger.
Parkbrau 'Pirminator' - High-octane seasonal beer made in the city of Pirmasens near the French border. Word to the wise... this beer WILL f*ck you up. Not very well known outside its local area, but the legend of its potency survives by word of mouth of current and former US servicemen stationed in Germany. (I drank two 'mortar shells' (what we called the 1/2 liter bottles) and was completely blotto in no time. No wonder they call it the 'Terminator'!

)
EKU 23 Doppelbock - Another high-octane brew, this is relatively easy to get in the States.
Dutch beers
If you like Heineken, the domestic version tastes a LOT better than the export version sold here. Amstel Light's not bad either.
Belgian
I'll go for many of the krieks and lambics (the fruit-flavored beers). Very good, and if you drink one too many, you'll find out real quick!
British ales and Irish stouts
My goodness, my Guinness!
Can't go wrong with a good pint of bitter. And a half-and-half works well for me too.