Adafruit (Edit was: Sparkfun) has TI's CC3000 wifi chip on breakout board with library on github. See
https://www.adafruit.com/products/1469
I ran some simple benchmarks (UDP and TCP) on DUE, teensy3*, and mega2560. I had to do a bit of hacking on the library to get a proof-of-concept to run on maple. The CC3000 SPI is spec'd at 16 mhz, but I got it to run at 18 mhz on maple (though not noticeably faster than 9 mhz tests?). Here are some preliminary test results
https://github.com/manitou48/DUEZoo/blob/master/cc3000.txt
Higher throughput could be achieved with SPI+DMA ...
(Edit: I took the liberty of changing sparkfun to adafruit, I looked at Sparkfun, but couldn't find the CC3000.
Please delete this comment if you like - gbulmer)