In object edit mode, be able to select a single object in a linked set, and be able to edit object's size/position itself without having to delink and relink.
Strattle animation. Sit is kewl, but when making something like a bike, sitting on it side-ways isn't gonna work too well.
A Phantom option where "Lock" and "Physics" are located in the object edit window.
The ability to have a single prim in a link set be phantom by itself.
A function that will have the object give itself to someone/something. Simular to llGiveInventory, but instead llGiveSelf(key id) which would give itself to a person/object. (This feature is desperately needed for a HUGE SL game I am developing which everyone in SL can play together at once)