In some places they are used to fight other animals, such as dogs, with wagers made on the outcome. A basilisk is able to tear a large dog to pieces.
Basilisks are venomous and are the source of basilisk venom. The Faceless Men use a paste spiced with basilisk blood, which gives meat a savory scent but induces a violent madness in any creature with warm blood, whether man or beast.
A Clash of Kings
When Daenerys Targaryen is visiting the docks at the port of Qarth she dismounts from her silver beside a gaming pit where a basilisk is tearing a big red dog to pieces amidst a shouting ring of sailors.