Well I don't really feel like typing a lot, but something like this would be fun. You log in, you can do something like ::master, :

etlevel, etc. Or you could have superrr fast experience rates. For items and money, i'd base the whole economy off of some kind of currency (whether it be tokkul, tokens, or just regular coins). Don't go making some items a "donator only" item. That makes it less fun.
Instead of making items "donator only", just make it so you can donate for them (to get them faster) or have a slim chance of getting them from a random drop/a certain kill count (somewhere along those lines).
Also this is a key feature; When a player kills another players; Their kill count goes up and they get a currency reward (a decent amount, ya know, not too big but not too small).
Oh yeah and as said above try and stay away from adding the custom and higher revision items; It just ruins all the fun. No one likes pking in the newer runescape so why not attract players by putting up the old school stuff.
