Alot of games give benefits from level alone. Most give minor bonuses stats or skill ups. Most of that wont work for RPG mo, so with that in mind, i provide the following. Every 5 or 10 lvl of CL one point of permanent speed. 10 would obviously be the best for numbers and game play. It wouldn't be game breaking at 10 nor would the added speed effect the game negatively. it wouldn't effect the current market on speed items etc. This avenue also brings up the possibility of other CL related things and it also brings up another big idea
Multi skill skills.
This should be another topic but im lazy and ready to type now. All multi skills are epic in nature and are not meant for beginning players but as another means to help make integrating all parts of the game over time as well as increasing high end player involvement.
Multi skill skills would be interesting in implementation and use/idea. A simple one could be something like [b]hunting[/b]. Hunting requires combat lvl 75 skills required two melee skills at or above 60 as well as archery and magic at 60. (sidenote for pures a high high hp requirement could be set. such as 105) This unlocks Hunting. Hunting is an interesting skill, you use another skill "engineering" (has other uses) to make various traps and devices. These traps and devices will allow you to trap wild creatures. Sold to different merchants, including a rare merchant who comes once a week in NML. All creatures will either be caught, "based on skill lvl" lost. losing the creature takes the device or traps. Only certain creatures can be caught.(creatures of varies types all are one. so if you catch black dragons your really just catching a generic dragon. making type not an issue and opening up the fact you can trap then kill the mob your hunting. this replenishes the mob to trap again). They can have 1 of 3 current uses. 1 to sell for coins from the various vendors, 2 to be used in various recipes from other skills, new items, etc; and 3 for another skill called "transmutation"( which happens to be a multiskill.
Transmutation is a multi skill involving magic alchemy and breeding. you need 75 magic 65 alchemy and 50 breeding to unlock the skill. this skill allows the possibility of transmuting one thing into another. for instance you use hunting and catch a hypothetical dragon. its just a dragon. no color or type. you then use a spell and have the required breeding lvl to transmute your dragon into 1 of several dragon related items of varied use and worth. such as scales horns rarely pets etc with a moderately high chance of failing.
Engineering. Skill needed HP 70 carpentry 50 woodcutting 50 mining 65 forging and jewelery and 60 each. Obviously makes the traps and devices but will have lots of other varied uses bringing value to other minor items that go tossed aside.
Brain storming would be interesting. im done here mostly I digressed and its just a spillage of info. I hope that something in here makes an impact.