Yes, you read it well: a fully functional Wifi module for only 3$, that you could connect to your next project using a Serial line. There are no excuses now to add Wifi functionality to your next project and forget about all the complicate TCP/IP stack protocol, you will handle the device by simple AT commands.
The module name is ESP8266, and their web page is https://github.com/esp8266. You could search for “ESP8266″ on ebay and find out that you could get this module with shipment included for as low as 3.50$. The module is provided with a PCB antenna, oscillator and other modules, for an stand alone functionality. It is powered by a 3.3v single supply and it can consume from 1uA on Standby, up to 215 uA @ 1Mbps @ +20dBm. It is interfaced by a serial line and controlled by AT commands.
For the more expert users, they also release the SDK, which means that you may not need to have an external microprocessor to control it. You could modify the base SDK code to add your functionalities, making use of the spare CPIOs and other modules, compile the code and upload to the ESP8266 module. Is it that crazy !!! This opens a great window of opportunities for low power and stand alone devices that could use low power wifi to transmit information.
I must say that I have not test them yet, but after Christmas I will give a try. Also, I will have time to think about how to get the best functionalities for my next projects that could use Wifi communicaitons.
Keep tuned for next projects using this module.