Where are you staying downtown? There are are considerable number of places where you can find good beer (Alewife, Max's, Pratt Street Alehouse, Metro, Brewer's Cask, Abbey Burger Bistro, etc.), it's hard to make a recommendation without knowing where you're staying and whether you have access to a car.
go East on Alieceanna or Boston and youl be in Beer Heaven or check here http://mqvibe.mapquest.com/us/md/baltimore/central-baltimore/#cat=7&poi=270974126
max's rocked...i had firestone double jack, FFF's boogoop, and some good locals.....brewers art resurrection i think it was....their crab pretzel was freakin amazing too.
