My Suggestions

I have several to mention.

High-Scores:

-This would be a great addition. Most people who play private servers are very competitive (example: look at PKing, and how ruthless people get). In my opinion, a high-scores feature would draw in tons of players. It would give them the chance to have their names put up in lights (figuratively speaking) for their achievements in-game.

Prayer Updates:

-As you may know, you can only increase Prayer with Dragon bones. This, however, is very discouraging for those attempting to achieve a high Prayer level. If I'm not mistaken, only one person on the server has 99 Prayer. It takes a very serious amount of time to obtain so many bones to get that level. Making all bones bury-able (don't make fun of my made up word loool) would be a great addition.

All Working Skills:

-Okay, okay. I admit that I am getting a little over-zealous with my wishes. However, all working skills would draw in quite a lot of people. Look at EuroScape for example. It has a booming population (or it did, I'm not really sure if it still does, but when I checked it out, it was huge).