Let me preface this by saying that I love to create total conversion style wow servers. I have made 2 and attempted a 3rd (things came up though).
I have been toying with the idea of people being able to pick what spells they wanted when they created their character and pick what talents they want too (as in any talent any class has by way of quest based npcs). Now this idea has merit no doubt, although it may have been done before. But then I came up with something else, something that would bypass the mana problem altogether (that being, warrior rogue and dk spells no costing mana and those classes not having mana for customization). A server based off of the idea that all spells are granted by items.
Not like books that teach you a spell, like items that have an ability tied to them (think goblin rocket launcher). So you would have to pick gear based on what spells it let you use so you could create the right mix for your character. It would allow the use of any spell in the entire game regardless of its normal cost and it would allow for additional limitations being applied to spells that could break the game if unchecked (think bubble+bladestorm+the dk's grabby arm ground thing).
Then with that in place a massive crafting setup (remove 2 skill limit ect) you could make the right gear setup for you. because there are so many spells, farming for the right stuff would take infinity+1 years with a properly made server. Then of course epic/instance gear would have maybe 2 or 3 usable spells (Dunno if thats buggy or w/e I have not tested it yet) so you could expand you're character more. And this would take place in a fully customized world (and by world I mean small area that gradually gets expanded).
So. Anyone have any ideas, input, flames for me? I would like to make and host a 3.0.9 server based on this (and probably will) so if anyone would want to play on it or would like to test stuff or even help me make it gimmie a shout.