Be careful of just getting a reprogrammer. There are a lot of systems out there that will reflash your computer and just dump a crapload of fuel into your engine, and it comes to a point where its bad. There is a little inline computer system from predator, that you can plug in and unplug quickly and easily that intercepts, and changes computer code for ya, its not as much power, but its cheap, its easy, and if you ever have problems you just unplug the little module and your good to go.
As for the rest, CAI and Exhaust and big, exhaust especially, get yourself a 4" (not 5... still need SOME backpressure) all the way back.
After that, you can get really crazy too, theres a new turbo out for them, a new tq convertor is definately a consideration when you start adding power. For about 800 bucks you can get new 85 (I think) fuel injectors that will give you over 100 some hp. Check out the sites that were already linked they have tonnes of stuff. Diesels are really easy to get tonnes of power out of. I mean, really, its just like the 6 gun works. With a diesel you can just turn a knob and double your power... put propane on, it cleans emmissions, makes you run cooler, increases fuel mileage, and engine longevity.. not many performance add ons for a gas engine that do that!
Good luck and enjoy your new dizzle powerd ram.

Believe me, the 600 (!) lb ft of tq will be a kick in the ass at first anyways. I know, I had one for two weeks before I decided to step down to the rumble bee (For 5000 dollars more!)
-adam
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2004 Rumble Bee Ram (Custom)
2 12" PG Titanium, in PG Truck Box
2 PG Tantrum 6x9
Powered by Alpine MRD-M501 Amp
and yeah.... Its got a HEMI!
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