The most direct way to improve acceleration is gearing...change your diff gears to a lower ratio (higher numerical ratio)...and you'll scoot off the line and accelerate faster, no problem.

Its expensive though, a few hundred per diff (And yes, you have to do both...).

You can also put in a freer flowing exhaust and intake, cold air induction, better headers, etc.

Do you off road it too? If you do, some of the options can be combined, if not, other options can become more advantageous, etc.

Do you do long hwy drives, or city type point and squirt driving, etc?