Charmed Labs XPort 2
The Charmed Labs XPort 2 can be combined with a Gameboy Advance, to use it as a MicroController. Since it uses an FPGA, and has flashrom for programming the ARM cpu, it gives you a versatile system.
It has 64 programmable digital IO ports.
The XPort may be extended further with the Robot Controller board, which has 4 PWM outputs -compatible with Lego motors. These are Closed Loop Motor ports with Back EMF Sensing- so they sense the motors rotation as well as powering them. The controller adds 8 digital and 8 analogue sensor inputs, and separate voltage supplies.
In a cheeky twist - the Xport Robot Controller has been given the acronym XRC - clearly a take on the Lego RCX. It is not compatible with Lego active sensors out of the box, but with this much programmability and an FPGA an emulation layer could probably be fashioned.
Being based on a GBA (Gameboy Advance) it has sound and a colour display.