In Australia, they call thongs what the rest of the world call flipflops. In Australia, such footwear is an important part of the lifestyle, so for those that need to wear foot orthotic, they either do not wear them or they do not wear this type of footwear. That is where these Archies Thongs come in. They were developed in Australia to provide some sort of arch support on a thong or flip flop:
They have about 2.5cm of arch support in them which is very similar to what most prefabricated or over-the-counter orthotics have in them, so they are a viable alternative or adjunct to foot orthotic therapy.
The Archies Arch Support Thongs are selling well in Australia and are highly recommended there by Podiatrists, who a lot of them use them for themselves and their families. For more on the Archies, see these links.