The absolute best I've seen is by Mike Fox with
skullTronix. Check out their Gallery to see the "Seance" routine. His own site of stuff prior to SkullTronix is
The Fox Productions Website. You can see some fun things there, as well as a tab for Voice Overs you can purchase. He did the voice for my pirate scene the first year I got into the talking skulls a couple/few years ago, and it was unbelievable!