since we don't have many players you should give us the ::yell ability because clan chats aren't always reliable. You have to take in the consideration of different time zones ,New players might not be informed about the cc because when we are logged off they are logged on. etc.
Maybe you can add custom weapons / Armour ( ex. mine craft Armour, double exp ring, glowing swords, morphing ability-like shape-shift into a car) you can put these items in the donator shop
maybe you can add a way to prestige skills after getting 99 in a certain skill. Since some players only play to level up rather than pk especially for now since we don't have many players. You can add prestiges up to 10 or something (like for example if you prestige your str 10 times to 99 - you are able to hit 10% harder) (or if you prestige prayer 10 times - your prayer lasts 2x times longer)
add a fun pk
add dicing, or lottery poll
high scores (idk if you have already though)
more to come