In fact, the only product that I can say with any certainty is slave-free is Cadbury's plain milk chocolate, due to the Fair Trade logo. (Check this useful comparative report of three such logos.)
What I want to see is legislation that requires full disclosure of each product's supply chain, and mandatory labelling that ensures slave-produced goods are labelled as such, so that I as a consumer have the right to choose slavery-free products. For a while there I got all excited thinking we could have a central database of supply-chains integrated into a barcode-scanning iPhone app such as Free2Work.
But the problem is it's not as simple as that:
"WHY NOT BOYCOTT? In certain situations boycotting specific goods or countries can actually make the situation worse and undermine the economy of an already poor country. A boycott could hurt those in slavery-like conditions as well as those employers who are not exploiting their workers, and worsen the poverty that is one of the root causes of the problem. Support fair and ethical trade initiatives instead and use consumer power to encourage retailers and companies to move to the Fairtrade scheme."