Add in Relics and other alignment related items (things that require you to have Light II or Dark IV, etc). These items would only be available if you remained within the Neutral Zone (that area between Dark I and Light I).
This would be great for RPers who want to play a truly neutral character, but do not want to lose out on the bonuses provided by Relics. This would also make your Light/Dark side choices have more meaning. Rather than just breezing through the game saying "I'm a darksider, so I'm going to choose every dark option that comes along", your choices will have a definite impact on your character.
This would still be on par with the Relics that are available, as maintaining that neutrality would get harder as your character leveled. So instead of having to be level 30 and Light II (or whatever, it's just an example) to get the next higher relic, you will have to be level 30 and still Neutral.