I'm looking for portable micro PC (uPC) on a stick (something like Raspberry Pi), but a lot smaller (a USB thumb drive size).

Any architecture is great (ARM is fine), as long as you can install Linux on it (so some storage is a must). Support for Wi-Fi is an advantage.

Here is which I've found so far: Forget Raspberry PI How About Android on a Stick!, but the article is a bit out-dated.