Barcelona's hyperactive tourist office offers plenty of information and maps, and can book last minute hotel reservations as well.
They run a number of popular guided tours in English.
They sponsor several money saving passes that are well worth looking into, including the Barcelona Card, the Bus Túristic, the Articket, Arqueoticket, and the Transport Passes.
They sell tickets for concerts, events, Barcelona and Espanyol football matches and other sporting events, museums, Flamenco shows and attractions, and often offer discounts on GoCars, Cooltra Scooters, and more if you use their website to book online in advance.
Image by Terrazzo