One ATmega 328 does pretty much everything to control the Droid. It does the sounds, the VFD control including the high voltage regulation, and the random movements for the dish antenna. I re-used my custom controller board that I use for my R2-D2 and that I call a "MarcDuino", which you can see here on the right, the purple board. I added the VFD driver and HV supply electronics on a prototype board underneath. 

In the above picture, you can also see the sound system consisting of an MP3Trigger from Sparkfun in the middle and an audio amplifier board to the left.

Here are the electronics at work, with the MarcDuino controlling the antenna, the front panel lights, the VFD and the sound. Another ATmega 328 controls the front panel lights.

The VFD driver is my adaptation of a clever design I found on the web, can't remember where. The high voltage is a boost circuit that uses the ATMega as the controller/regulator. Very simple: monitors the voltage on one of the anaIog pins, and varies the duty cycle of the MOSFET switching accordingly. I will upload the schematic in the files section.

Here it is all wired up. Since the RC car battery voltage is sort of in the middle, there is a voltage upconverter for the 12V of the audio amplifier and a downconverter for the 5V of the ATMega 328 board and other electronics on a little side board at the bottom. The high voltage VFD supply is on the board below the ATMega board and is regulated by the ATMega.