If a KERS equiped car spun and killed its engine, it might be able to get going again using its KERS power to refire its engine, and continue racing. I'm not sure if this would actually work, but I'd be willing to bet they're trying to make it possible.
Anyone know if any of the F1 KERS systems have been used in this way yet?
Another potential KERS advantage - reverse. A car with KERS could use that power source to run the car in reverse, and thus might be able to completely eliminate the reverse gear in its transmission. This would save weight and size in an aero critical area.