This router from HooToo is amazing: $18 for the HooToo Tripmate Nano. Ethernet in, 802.11 b/g/n out, and it acts like a router, bridge, can even serve SMB with a USB disk. And the thing is about 2×2 inches, less than half the size of a pack of cards. $18!
No idea how it works as a bulletproof serious router. I bought it for travel, in particular for hostile hotels that either have no WiFi, bad WiFi, or want to charge you per device. If they have an ethernet cable you’re usually better off than trying their wireless.
$18! How is that possible? Particularly the 802.11n chip. It’s an American company too, or at least they list an address in San Jose. (English is awfully bad on the site.) Hardware design is cheap, obviously, but seems solid enough.
The firmware is clearly some Linux derivative. The Nano just offers a binary, which I unpacked as far as to see it was an initrd image. Another product of theirs includes a “GPL Source download” so they’ve at least heard of open source license requirements.