Spider web pizza (google it) uses mozarrella cheese cut into thin strips.sort of constructed like a wheel.
tomato on bases and strips added equals pizza maqheriata
Pop spider on afterwards (made of black icing?) or a plastic one? or even play dough as it doesn't need to go in the oven.
Also there is a 'nice' pot of 'human brains' which you can hide presents in, bit like a lucky dip.
Use cut up cold sphagetti for this, or porridge coloured pink or red for cheapness and the 'yuk zombie' factor...
don't forget to wrap small pressies in cling film before they go in. This was a hit at a zombie party dd went to years ago, very cheap. Just be prepared as at the word zombile they scream for hours on end, but are exhausted afterwards...
painting