It's always best to cover you ass in these situations. Something along the lines of 'Xyz provide links to websites that are beyond our control. Xyz are not responsible for content outside of the domain http://xyz.com and visitors enter them at their own risk. Xyz will take no responsibility for damage to a person or property when visiting other websites.' And then maybe something along the lines of 'best endeavours' to check links that are posted...just to soften the blow a bit.