Aass is the namesake of both Norway's oldest brewery and the beers it produces. Built in 1834, in Drammen (25 miles south of Oslo), the brewery ("Aass Bryggeri", in Norwegian) has been owned since 1860 by the Aass family; the first owner was Poul Lauritz Aass, and four generations later, it is still owned by the Aass family.

Like many other European breweries, Aass is a strict adherent to The Bavarian Purity Law of 1516, also known as "The German Purity Law", or Reinheitsgebot. The brewery produces a wide variety of lager products that are marketed under the same name; four of these are produced for the US market, and are distributed through 22 different distributors in different states:
More information can be found at Aass' website, http://aass.no; Should you not be Norsk, they conveniently have an American-english site as well, at http://www.aass.no/usa/us.htm.

Oh, and should there be any questions as to the pronunciation of the name ("Hmm, this beer tastes like Aass!"), it is properly pronounced "Ouse".

Works Referenced:
Aass Brewery webpage - http://www.aass.no/usa/us.htm
"Reinheitsgebot: Germany's Purity Law" - http://hbd.org/brewery/library/ReinHeit.html