Ok, so the first couple of images i posted showed no more than a sensor on a servo.  Since then i've put together a wheelbase (not the most efficient setup, but it serves a purpose for the moment), added a bluetooth connection, and an IR avoidance sensor.  

The wheelbase is made from a couple of motors and gearboxes salvaged from an old robot toy.  Sadly these are massively power hungry, and so the drive batteries don't last very long at all.  

I've used an uber cheap HC-06 bluetooth module from ebay for wireless communication, and although it was fussy at the start, it seems to stream the data nicely.  Sadly however i've not figured out a way of putting it to sleep when it's not in use, causing more of a power drain on the system.  Coupled with the cheap servo the arduino is also drawing it's fair share of current (although from a different set of batteries from the motors).   

 Next step is definitely to sort out the power issues.  Hopefully starting with the control side, and shutting down both the servo, bluetooth, and possibly even the ultrasonic sensor when they are not needed.