I vote for a small router reflashed with OpenWrt like "TP-Link TL-WR703N".
It is like building an own Yùn with an Arduino of your choice...
The WR703N:
It has Ethernet, 150MBit WiFi, USB and if you want to solder, a serial console and 2 GPIO-Pins which can be turned into I2C.
This sure is not a chip- or stamp-sized solution but often cheaper than the alternatives, more powerfull and extendable.
Search the net with your favourite find'o'bot for "arduino wr703n" and you'll find lots of examples...