Dunks:
An assortment of simple dunks, including:
- One handed dunk, standing
- One handed dunk, off the dribble
- Two handed dunk, standing
- Two handed dunk, off the dribble
There would be variations of each, including hanging on the rim and varying degrees of power.
An assortment of powerful tomahawks and two handed slams, available for dunking in traffic and adding emphasis on the fast break or in the open court. Further variations on the basic one and two handed dunks. Also, some of the simple dunks after taking off further away from the basket.
Two handed reverse dunks, from a few angles and with varying power, with a couple of them involving hanging on the rim. Also a couple of one handed reverse dunks, mostly simple.
Windmill dunks in a few styles, including great extension (a la Dominique Wilkins) and less extension (think Steve Francis in the dunk contest a few years ago).
Between-the-legs - Practice Mode only. Or the dunk contest, if it's in the game.
One handed 360, available spinning in both directions. Varying degrees of power.
Two handed 360, available spinning in both directions. Varying degress of power, with not all of them resulting in the player hanging on the rim.
Free throw line dunk, mostly occuring in practice mode. Also a few near-free throw line dunks which could occur a little more often in gameplay than the free throw line dunk.
Statue of Liberty dunk, and Statue of Liberty 360.
A few more double pump dunks, including double pump reverse dunks.
Layups:
The basic layups in NBA Live 2004 are already realistic, so I don't really have much to say about that. However...
When running under the basket, it should be possible to automatically execute a reverse layup as you could in NBA Live 2002. A little more control over reverse layups would be great.
Various up-and-under layups, include "Jordanesque" layups and other more basic up-and-under moves...and maybe a few spectacular ones for specific players.
Dr J's Scoop Up and Under (behind the backboard) - for Dr J only.
Dunk Packages
A couple of layup-only packages.
A couple of "rarely dunks" packages, with one being mostly layups with a couple of one handed dunks, and the other including a couple of two handed dunks in addition to the layups and one handed dunks.
An assortment of basic dunk packages:
- Only one handed dunks
- Only two handed dunks
- Mostly one handed dunks, with a couple of two handed dunks
- Mostly two handed dunks, with a couple of one handed dunks
- A few mixtures of one and two handed dunks
- Mostly basic one handed dunks with a couple of fancier dunks
- Mostly basic two handed dunks with a couple of fancier dunks
- A few mixtures of one and two handed dunks with a couple of fancier dunks
There would be a few variations suitable for more athletic/less athletic and shorter/taller players.
An assortment of spectacular dunk packages, each with plenty of basic dunks (see above for the kind of variations of the packages)
A couple of dunk packages that include pretty every dunk in the game.
A few player-specific dunk packages (I think that's a great idea ruffryder

).
That's about all I can think of at the moment.