The reder has been poorly done... I can see white bits. In fact, I'm sure you could find a better render all togethor of sub-zero. The bg, if I'm not mistaken, is teh cloud filter. Try something a little more inventive. An ice effect bg would fit in very well with sub-zero. Use fractals.
Umm... the bg should be more white rather than blue because of his power of ice. I would also advice you to get rid of the animation alltogether.
You should also add a border, get a better font and finish off your text better...
(And now I feel really bad because I've took your sig apart, lol)