pcDuino: mini PC + Arduino
http://www.pcduino.com/

new piece of hardware for a cool price of only 59,- EUR
with more power as rasberry pi (of costs of energy consumption)
http://www.exp-tech.de/Mainboards/pcDuino-Dev-Board.html

mini Linux PC (Ubuntu 12.04), so we are happy to use Python to handle the full set of Arduino IO Pins on this board. The  Arduino IO Pins are not located exactly as they are on Arduino Uno Rev3.. but an Adapter Plate will solve that.

Raspberry Pi vs. pcDuino:
http://raspberrypihax.net/pcduino-competition-that-could-take-on-the-raspberry-pi/

59,- Euro ONLY.. exceptional price..
A battery voltage logger based on arduino cost the same..
Arduino UNO Rev 3: 25,- Euro
mSD Shield RTC+miniSDcard: 18,- Euro
ADS1015 12bit ADC: 10,- Euro
Grove Voltage Divider: 6,- Euro
Sum: 59,- Euro

the pcDuino gives you SDcard,12 bit ADC , 10-bit ADC only,
but no RTC?
BUT you get USB for standard Wifi components..which costs many bugs as native arduino shields! thats a huge pricy advantage.
https://s3.amazonaws.com/pcduino/User+Guide/pcDuino+arduino+environment.pdf