Looking for recommendations from the masses that balance performance and cost.

Just bought a 2008 Mega 1500, 21,000 miles, 4x4, Hemi, 5 spd auto, stock suspension and tires, and 3.73 gears. Doing searches through the threads, recommendations for better (relative to a Mega) MPG seem to include:

CAI - I am working on this one.
Exhaust - Cat back most likely.
Tuner - Likely will be Predator.
efan - Have no idea. Are there preferences?
taller gears (4.10+) - Unlikely this will occur in near term. Plus, wouldn't 3.73 on stockers be somewhat close to 4.10's on 37's?

I'm looking for practical advice that includes personal experience and advice that balances performance increases with cost.

Thanks in advance.