Finally have a preliminary PID routine up and running on one of my line followers. Its taking the 8 front sensors and coming them together into a single value ranging from 1000 (left) to 8000 (right) with a value of 4500 being the centre. From there I jam it into an incredibly simple PID routine and use that to drive the motors. When it loses the time, it stops the PID and turns towards whichever outside sensor last saw a line (for right angle turns and whatever). Its all completely untuned at this point, so its amazing that it is doing as well as it is. ;-)