Today’s tutorial is a bit different: I’m going to show you how to make your ethernet shield wireless!
Sometimes however it could be easier (and maybe cheaper!) to connect an Arduino to the Wi-fi network using your ethernet shield in conjunction with a wireless router.
I found the TL-WR702N nano router by TP-LINK that, with a cost of about 20€ on eBay, can work also as a wireless client: in this mode the router acts like a “bridge” between the device connected to its ethernet port and a Wi-fi network.
The TL-WR702N router is also very small and you can power it through a micro USB connector:
For more detail: A cheap WiFi interface for Arduino