Hey, this is Shaun and I am suggesting Skill points. The idea is that when you get to a certain point in a skill, (For example 80 theiving), you start getting skill points everytime you theive from the level 80 stall. The amount could vary depending on the difficulty of the skill. There would be a shop where you could purchase items (preferably 1 defence equips for skillers), for skill points. The skills that would be most easily compatible would be Woodcutting, Theiving, Fletching, Crafting, Farming, Cooking, Firemaking, and Fishing. Also, when you get to 80, 90, and then 99 of one of the compatible skills you get a high number of skill points. It would increase on each one, the lowest amount for 80, higher for 90, then the highest amount for 99. I have suggested this idea to servers before, and it has increased the amount of players because it gives people who like to skill a reason to, and it the server's economy isn't entirely based off of combat.
Thanks for reading and I hope you take this idea into consideration.