I came across two fun ones one of which I actually set out to make and my boys are now enjoying counting down the days till Halloween.

Let me introduce you to our Halloween advent calendar! The idea is that each day of October, you eat a piece of candy and look forward to Halloween! Mr. Oopsey Daisy doesn't enjoy sweets all that much, so it's just lil' old me! Eat a piece of candy every day?! Yep, I can do that!! Click here for full artciel and step by step instructions.
Here is a 2nd one it is from Craft Critters that looks like a fun project that kids will enjoy counting the days till Halloween with. Click here for complete step by step instructions.