With Arduino being open-source, the design is easy to expand upon to create your own board with additional features. With the rise of Kickstarter, it's now easy to get the funding for projects to produce for the masses. It's no surprise that there's a lot of Arduino-type boards popping up.
The DigiX (by the makers of awesomely tiny Digispark) is one of these boards. It's an Arduino Due compatible board, with onboard WiFi and Audio capabilities - 2 of the major limitations of the Arduino. The DigiX is powered by a 32-bit ARM MCU and features an extra 25 digital I/O ins over the Due/Mega 2560. These extra pins are added so existing Arduino shields will still work with this board. It features a real-time clock, which again is one up on the Arduino., plus a whole host of different communication protocols (4x UARTs, 2x I2C, SPI, CAN Bus, 2x DAC, JTAG, DMA).
The USB feature on this board is also very interesting. Similarly to most Arduinos, you upload code via USB. However, it can act as a keyboard or mouse, and even as a host, allowing you to connect peripherals to it fow instant control. As it's a host, it can also allow you to connect an Android device and program with the Android ADK. WiFi is another story though. With Arduino, you need to either make your own WiFi module, or buy a shield to incorporate this functionality. The DigiX has an on-board, low-power WiFi module, which promises easy setup. Commands can either be sent via standard Serial commands, of use the supplied libraries to push, fetch and serve data.
Capable of performing any task the Arduino Due can do with 100% compatibility with projects and shields, DigiX looks to be a winner in the field. It's only slightly more expensive than the Due, but works out a lot cheaper if you count the WiFi and all the other little extras it has.
The DigiX is a Kickstarter campaign, that's already reached it's goal. However, you can still donate, and if they reach a higher target, they will add onboard EEPROM and MicroSD card slot. Not bad for $59.
EDIT: The Kickstarter campaign has finished, but you can pre order directly from Digistump. As they smashed their target, they will be adding the EEPROM and MicroSD card slot, with the price staying at $59.