I have begun work on my own rpg. It is being designed around the shonen manga genre and I hope it can be used to emulate different games. Its got a long long way to go though, but every now and again I find myself coming back and messing around with the mechanics.
The core of my game is similar to d20 in a way, roll d20 for attribute checks plus number. Characters have many ways to fight, hand to hand, melee, guns and magic. Magic is a default term and to be honest i am considering using the term SFX to define special effects.
Characters also get bursts of power that trigger from their emotional state, can get special forms etc. I am also designing a way to consider power creep in a scale that keeps the numbers lower to avoid dice breakage (basically in dbz rpg, 3d6 no longer matters when people break that limit).
I am currently done with my first draft of the core system and am working on the powers subsystems. I want to make the powers somewhat modular, if your game has characters that can make up powers on the fly, you can do that. If you only get so many abilities at first then must spend in game time learning you can do that too. Pretty bold and difficult to do alone.
Because I hope to actually sell this game as a pdf (dirt cheap) I hesitate to provide too much information here.