Can't post links right now but:
Sigil of Necromancy
Item Level 665
Use: Slain players and creatures summon a Skeletal Warrior or Mage at the command of the Death Knight. The Death Knight can have up to 3 Summons at one time.
Classes: Death Knight
Requires Level 100
Sell Price: 1c
This looks really cool, there's a few other items like this for other classes as well. I wonder if these will be on-use stackable items or if they will apply the effect permanently. Either way, this looks cool!