I think they're more common in countries with poor safety regulation of electric devices.
This adaptor strip/board was at my hostel in Tbilisi, Georgia at the time the question was first asked:
It seems to be made by a company called "Veto" with model number 606F, but I couldn't find anything by Googling.
And a few days ago I found a "bin" full of these in one of the very few supermarkets here in Vientiane, Laos:
Chinese labelled imports.
Now that I've spent a month travelling through China I can say without doubt that it is the golden country for these devices. There are a myriad variety of them on sale everywhere. These photos are from a supermarket, not an electricial or electronics store, and it's in a city most Chinese haven't even heard of:
Typical range in a typical supermerket anywhere in mainland China.
The one I chose was compact and seemed to be a decent quality. It has two sockets for two- or three-prong plugs and one for only two-prong plugs. The three-prong sockets accept Australian style plugs and Europe/India style plugs. They also accept a style with two flat prongs that works in Taiwan and probably other places. The plug on the other end of the adaptor is Australian and Chinese-style three-prong.
Yet I don't think I've ever seen something like this in Australia. We have no shortage of supermarkets and electronics shops with tons of adaptors and powerboards but we have quite stringent safety standards on electrical products.