of interest - there is a new beer bar (or perhaps one might call it 'gastropub') called ALEHouse in Riga.
and it is, as far as I know, the only place you can get Sam Adams (in bottles) in Riga. In fact they have quite a large selection of American beers there. The place itself is slightly fancier than the average Riga pub. The beer, despite being imported, is fairly cheap, though the food is slightly more expensive than an average meal.
Lāčplēša iela 12 (just off Brivibas). Is where the vegetarian restaurant Kamadena used to be.
I am not in any way associated with the place, but thought it might be of interest to the local and tourist beer drinkers!