One idea - and I just now thought of this and thus it has exactly zero playtesting or math analysis to back it up - might be to use d% instead of d20, and in order to to give a bell curve always read the dice such that you take the result closest to 50. Thus, if you've a 1 on one die and a 5 on the other that'd be 51 (no matter which particular die the 5 was on). The range would be reduced such that in effect it's be a bell-curved d-90, as anything with a 0 would by this method become a multiple of 10 rather than '0x' as the multiple of 10 will always be closer to 50.
The advantage of this is simple: more granularity, thus giving more range and-or options for any given roll. Along with this comes a greater range of possible bonuses/penalties - a +1 here doesn't mean nearly as much as on a 3d6 or 2d10 curve; but you can still have it, or +2 or +3 or whatever. +5 would be more or less the same +1 on 2d10 but still worse than +1 on 3d6.
The tricky part would be training ourselves to read the dice the right way to make this work.