Geron Raveneye
Explorer
Strictly from the 3E core books, or simply D20 magic systems? Because then you simply hit a floodgate of optional, but working, systems. The only caveat is that you shouldn't try to make too many of them work side by side.
I wonder at a lot of posters calling the standard D&D magic system "outmoded", "outdated", or any other derogatory terms. It simply is one way of representing a system for spellcasting. You can have all other kinds of flavours with D&D/D20 too, like mana-based systems (for easy access, replace the wizard with the psion, replace the psionic stuff with the spells, and you're done), you can have feats & skills, you can have a system where magic costs life energy (see Midnight, where it takes a while to cast mighty spells and can daze you (Sovereign Stone and a half-dozen other variants. Even something like Arcana Unearthed, that combined the flexibility of the sorcerer with the variety of the wizard.
The only thing I'd hate to see is a wizard who constantly throws magic around without really paying something for it, for the simple reason that it will make magic even more everyday than it already is in 3E with the overflow of magical items and magically endowed classes/prestige classes. Being a wizard used to be not about the "blasts per encounter" ability, but about the role of intelligent and mysterious worker of a force that only a few can master, and that can defy the laws of reality.
But on the other hand...from what I got so far about the changes in 4E, I'm not the target audience for the new edition by FAR. Which is okay, too, since it is also about bringing in new blood...and if the powers that be think giving the new blood shiny powers that never wane, or will be back in time to kill the next pack of monsters, then I'm sure they have a damn good reason for that.
And after all, I never used to play with the "old grognards" back then either when I started out. We were a bunch of teens and a few Basic Sets, and all that complicated AD&D stuff that the "adult" players preferred was just one more reason we stayed among ourselves.
So maybe, 3E will turn out to be the AD&D of modern D&D history, and 4E will be the edition that pulls in the current "video game" generation. Who knows. It would be for the good of the hobby for sure. 
I wonder at a lot of posters calling the standard D&D magic system "outmoded", "outdated", or any other derogatory terms. It simply is one way of representing a system for spellcasting. You can have all other kinds of flavours with D&D/D20 too, like mana-based systems (for easy access, replace the wizard with the psion, replace the psionic stuff with the spells, and you're done), you can have feats & skills, you can have a system where magic costs life energy (see Midnight, where it takes a while to cast mighty spells and can daze you (Sovereign Stone and a half-dozen other variants. Even something like Arcana Unearthed, that combined the flexibility of the sorcerer with the variety of the wizard.
The only thing I'd hate to see is a wizard who constantly throws magic around without really paying something for it, for the simple reason that it will make magic even more everyday than it already is in 3E with the overflow of magical items and magically endowed classes/prestige classes. Being a wizard used to be not about the "blasts per encounter" ability, but about the role of intelligent and mysterious worker of a force that only a few can master, and that can defy the laws of reality.
But on the other hand...from what I got so far about the changes in 4E, I'm not the target audience for the new edition by FAR. Which is okay, too, since it is also about bringing in new blood...and if the powers that be think giving the new blood shiny powers that never wane, or will be back in time to kill the next pack of monsters, then I'm sure they have a damn good reason for that.

And after all, I never used to play with the "old grognards" back then either when I started out. We were a bunch of teens and a few Basic Sets, and all that complicated AD&D stuff that the "adult" players preferred was just one more reason we stayed among ourselves.

