Want to convert your Arduino project to an Internet of Things one? Or wanna control the Arduino board from Internet or local network? Adafruit's wifi shield will do it for you. This is a part of HUZZAH series, Adafruit's Internet of Things compatible products and will also work with Adafruit.io.
CC3000 is a Wifi chip from Texas Instruments which is a sweet combination of features, usability and cost. It uses SPI for communication (not UART!) so you can push data as fast as you want or as slow as you want. It has a proper interrupt system with IRQ pin so you can have asynchronous connections. It supports 802.11b/g, open/WEP/WPA/WPA2 security, TKIP & AES. A built in TCP/IP stack with a "BSD socket" interface. TCP and UDP in both client and server mode, up to 4 concurrent sockets. It does not support "AP" mode, it can connect to an access point but it cannot be an access point.
This CC3000 Wifi Shield has a micro SD card slot, reset button, 3.3V regulator with 350mA peak current and a 3 or 5V level shifter. It also comes with an onboard antenna. Works with Arduino Uno, Mega and Leonardo/MicroCC3000 HUZZAH Wifi Breakout Board.