ORIGINAL: Wight
Do a google search for Chaos Space marines for Warhammer 40000.
They use lots of spikey bits and skulls on thier tanks etc,may be just the inspiration you need.
The imperial guard for 40k even use a tank called the hellhound.
Well, thanks for the direction on the Warhammer tanks.........., just googled it, I don't want my tank to remotely resemble something that's been done (artist in me) which this idea would be in the same class....so, I guess this idea is going to have to either go a different path or get real extreme.