How to Strobist a halloween themed wedding

Just got a call this evening to do a Halloween themed wedding (like the Nightmare before Christmas) this Friday evening. It will be at 5pm so right at sunset. The back yard is to be decorated like a cemetery and the actual ceremony will be done in the garage that will also be decorated.Need ideas and suggestions on what would be cool ways to use off camera flash to add to the "mood" and get excellent pics. I have 2 canon 580EX's, 2 canon 550EX's, and a canon 420EX.

How cool. For an interesting creepy effect, put a flash on the floor, controlled wirelessly, shooting up (think flashlight under the chin). Or bounce your flash off the floor.

Put a wireless flash inside a pumpkin and have them look down at the pumpkin. It'll look lik the pumpkin is glowing. Cool effect

Find yourself some dry ice for the fog/smoke effect. I buy mine from a welding supply shop. I'm not sure what they use it for but it works great for special effects. You put it in a little water to activate it and then have a light fan behind it to move it about. When I buy it I am required to sign a document stating what I am using it for. If you have multiple flashes you can put some with different colored gels to have the dry ice pickup those colors. Failing that a simple lamp will do the same.