Magnolia Brewing Company has some vegan options

Company email (May 2015):
"At this time, we do not use isinglass or similar products during clarification of our beer so most of our beers are vegan. We have used isinglass in the past but switched to a seaweed-based product.

We do brew a couple of special beers that use animal products, most notably our oyster stout that is made with oysters. We also make a very limited release beer for a local event that uses bacon.

All of our beer is currently made at our two breweries in San Francisco."