On my Razer Naga, I cut small rectangular pieces from the adhesive-backed hook (male) side of Velcro and attach them to selected thumb buttons. These tactile markers provide raised reference points that help me quickly identify and remember assigned game actions by touch, without having to look at the keypad or fumble around the buttons with my thumb.
Razer should offer custom clear or smoked-clear tactile markers designed for the Naga's side buttons. The markers would allow the backlit key numbers to show through while providing tactile reference points for faster button identification by feel.