I recently rebuilt my previous OpenWRT based robot. Focused primarily on reducing its size, I replaced the bulky L298 motor driver with a much more appropriate DRV8833. Redesigning the pan-tilt mechanism, and replacing the MSP430 with a more compact ARM Cortex board further reduced the robots size.
The TL-WR703N router was modified with the addition of a four port USB hub and 4GB flash drive within the original enclosure. Power and USB lines run through a header on the right side to the voltage regulator and microcontroller within the chassis.