I'm also very keen on the 'blu-spot' led laser spot lamps that project the blue spot on the floor. First saw them a couple of years ago in a large distribution centre and it's the first time in a long time I've thought 'that's a damned good idea!', particularly around doorways and racking aisle entry/exit points.
Other than a traction alarm (like a back up alarm but always on when driving) there is not a lot else you can do.
A rotating, halogen bulb type beacon makes the approach of a machine a lot more obvious than a xenon flashing type but they are VERY obtrusive in lower light conditions.
You can get adjustable volume alarms so you can dial it in just right, enough to alert people but not so much to drive the operator nuts!
THE BEST policy though is just to try to do as much as possible to segregate pedestrians/workers from forklift traffic as best as practically possible.