You'll forgive me for talking about how to remove 4e's homogeneity on this thread, I hope
First of all, there's nothing wrong with a power-based system. That's not the problem; the problem is that everyone seems to access and recharge those powers in the same way. Let's look at past editions' spells: they were the same "system" (fire and forget, levels, and so on), but each class added their flavor on top of that:
* Wizards had their spellbooks, and then decided in advance which spells they prepared each day. They could specialize in one or another school, and that changed the kind of spells they could choose from.
* Clerics had access to all the spells of the class, and they decided in advance which ones they prepared each day. They also had domains which added some more available spells.
* Sorcerers had a limited range of spells known, but they didn't need to prepare them in advance, and had more quantity of lower-level spells than wizards.
I don't see why something like that couldn't be ported into 4e. Wizards could be able to choose their at-wills and encounter powers (not just dailies) each day, Fighters could burn healing surges to recharge their powers, Sorcerers could spend a daily to recharge their encounters, Rangers could recharge when killing their quarry, and so on.
And I don't think it's all written on stone, either. If PHB2 could "update" the way some PHB1 things worked, there's no obstacle for PHB3 to include a chapter on "Power recharge by source/role/class".
I think something like this would remove part of the perceived sameness of 4e. It might work for me, at least. And that's an important thing, because I'm aching to play in the new Forgotten Realms or the next iteration of Dark Sun
