Have a green Halloween. Plenty Magazine has some ideas for celebrating Halloween without making a big impact on the earth. At the top of their list is to make Halloween costumes from things you already own.
For kids, they suggest dressing all in green with rows of rolled tube socks pinned down your front to portray a caterpillar.
A few more tips:
Have your kids use a pillow case as a candy sack rather than something plastic
Try to buy candy to give out that is low-trash, organic or for a good cause
Make a point to carpool to Halloween parties and events
Lastly, beware of vampires! Vampire electronics that is. Unplug electronics and appliances when not in use (40% of microwaves expend more power in standby mode than when cooking, for example) or plug everything into power strips with kill switches.