While not as convenient as wireless to your Arduino, sometimes good ol’ ethernet is the way to go. These cheap enc28J60 modules can be found on ebay for a lot less then a shield will run you. The enc28j60 uses SPI to communicate. So after connecting the pins in the right places, and using some of the libraries from the Ethernet shield you’ll be up and running in no time.
I don’t think that I really need to mention the possible applications here, as they are endless! But I would be wary of your data rate, I don’t think you’ll be streaming 1080p video over this thing but it is good enough to control stuff / send images and sensor data.
Read the article for more including a demo sketch.