Not at all, I was thinking of various things, amongst those forcing down demons & devils to inhabit the bodies of the dead. Also, I am working on introducing spirits (in the way they are represented in such mythologies as the American-Indian and Greek/Roman ones).hope that it doesn't border too much with summoning
Have you seen the Mechanithrall in the Monsternomicon from Privateer Press? It would be cool to have rules to create such a creature (there is already rules to create undead thrall in the book plus a bit in the errata, but the mechanithrall miss such rules).
An armor that grant undead immunities.
An amulet that make mindless undead to consider you like one of their own.
A weapon that graft itself to your hand/arm (a psionic spell can do this), and allow an undead to use its level drain / cold damage abilities through it (undead can't normaly do this).
Something really evil, and that player won't expect, a template that make the attack of an undead linked to an element (acid), grant immunity to all other (sonic, fire, electricity, cold) and weakness to acid
Secret College of Necromancy had a funny spell that recalled a spirit in a skull, and it was possible to do it on a skeleton, and to allow it to control its body. My idea would be to grant ECL to the mindless undead, just in case someone grant them intelligence, it could fun.
Something that I found strange in the first PDF was that it was really hard to build a permanent undead army, so perhaps including the legion spells from the secret college of necromancy would be good?
A spell that allow a vampire or liche to trade some or all of its immunity to become partially or totally human again for a time.
Clay_More said:
Thats actually a cruel idea, having a creature that has an acid attack have weakness to acid (something that the players most definitely wont see comming). Like having a water elemental with cold vulnerability. Yet, there would have to be a "relatively" logical reason why the undead would have such an odd combination of abilities / immunities.
I finished my proposal for a new Necromancer Base Class a few days ago. One of the things I gave them was an increased ability to command undeads, since it would help explain why a Necromancer could possibly create a large army (not only a small band of 10-15 zombies like a PhB wizard can). Many of the things I am working on are items specifically made for undead armies.
Easy one, a graft (symbiot/mechanicall/mystic symbol), use the negative energy/flesh of the undead to power the energy (acid/cold/etc..) attack, reversing the process will put the negative energy/flesh in the wrong place: boom!
For a base class, please try to make it balanced for PC, not for NPC (like Secret College of Necromancy did with its death knight and necromancer).
Thanks for your answer

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.