First off, Deal’s website (it’s a party Palooza) is a great site for ideas. I highly suggest you check it out!
Second, check out the recipe section of the forums. There are some awesome recipes posted up for snacks, treats, and cakes.
Dirt cake is a staple, and tasty. I have never seen a child NOT eat it : http://community.buycostumes.com/forums/t/Dirt-Cake-So-good/939.aspx
Another fun idea is take white cake and dye it orange (or orange box cake) and chocolate cake, and mix them separately, then swirl them together in the cake pans. Makes a neat Halloween colored marble swirl cake. Then top it with crushed Oreos or double chocolate cookies (super fine crushed, maybe put them in a Ziploc and let your kids go to town beating them up) and then put cookies with RIP on them in half way as tomb stones and gummies worms like you would a dirt cake.
Also, if you look here, there are more cute ideas. The popcorn hand bags would be cute for kids and adults as take home gifts, and who doesn’t like popcorn? You could always make cheese and caramel popcorn to! I use this bowl as my popcorn bowl. It’s HUGE and I love it to bits! I use it all year round.
Spooky Bowl: http://www.buycostumes.com/14-Spooky-Bowl/35200/ProductDetail.aspx