Walled City is technically a restaurant and can't serve pints without serving food but they're not always sticklers for the rule. They do small tapas dishes too if it's an issue.
Right at the bus station is a new pub called Blackbird, it has a Galway Bay, Whitewater, Northbound, Kinnegar and Brewdog tap as well as some bottles. Round the corner is a little bar called Sandinos that has a nice selection of bottled Belgians(no sours) and German beers, as well as a few Irish.
Across from the Ice Wharf is The Grand Central. They have Kinnegar on tap and a range of bottles too. They are due to launch their own range from Dopey Dick Brewing Co so depending on when you're up you might get to taste that as well.
Otherwise you should find Northbound bottles nearly everywhere now.
