My personal favorite so far is the Gray Philosopher:
"A Chaotic cleric who died with some important philosophicaldeliberations unresolved in his or her mind. In its undeadstate, the philosopher does nothing but ponder theseweighty matters. However it seems always unable toreach a conclusion. Over the centuries, the evil notionsof the philosopher take on substance and gain a will oftheir own. These animated thoughts, known as malices,appear as small, luminous, translucent wisps with vaguelyhuman faces, gaping maws, and spindly, clawed hands.They fly through the air, constantly searching for victimson which to vent their petty, but eternal, spite. Malices donot stray more than 100 feet from their philosopher, butare able to squeeze through the narrowest of gaps in theirwanderings. A gray philosopher typically creates 2d4malices for each century of its deliberations. Clerics turnmalices as spectres.Malices have the same attack rolls as a 9 Hit Dicecreature, and the amount of damage done depends onthe alignment of the victim: Id6 points of damage forchaotic characters, 1 d8 for neutral characters and 1 d 10 forlawful characters.The philosopher itself appears as a seated, gray,insubstantial, robed figure who is deep in thought. Itcannot be turned by a cleric, has no attack of its own, andwill not defend itself. Until it is actually destroyed, itsconcentration will not be broken even if it is attacked.When its moment of destaiction comes, however, it willlook up with an expression of malicious enlightenmenton its face and then vanish with a lingering scream of evildelight. All malices vanish instantly when the philosopheris destroyed.Both the philosopher and the malices are immune tomind-affecting magic (charm, phantasmal force, etc.)and to attacks from nonmagical weapons."
Also, If you all get the chance check out Radio Rivendell. I know it isn't a new thing but I just discovered it and it is bloody awesome!