RFXduino: Wireless Ethernet/Internet over nRF24L01+ modules for Arduinos!
What is it? RFXduino provides Wifi capability for up to 255 Arduino (or compatible) devices equipped only with inexpensive nRF24L01+ modules, by sharing a single Raspberry Pi connected to your LAN as a wireless TCP/IP gateway server.
Send emails, tweets, access http and https servers, serve web pages from your Arduinos