A Halloween costume hat can come in pretty handy. It works as a last minute costume, or you can bring it along if you’re not sure the party requires costumes or not. It will keep you warm while you stumble around in a midnight corn maze and it’s great for costume day at work if lugging fairy wings home on the subway is impractical. If you knit or crochet there are some great patterns out there.
Also at Knitty is this pattern for the Desperate Housefrau, a knitted wig in curlers.
Forums like Craftster and ThreadBanger are great for inspiration and ideas. I love this knitted Monster Hat and Scarf, the scarf pull through is clever. The crocheted Elf or Faun Earflap Hat is perfect for cold nights watching over tireless trick or treaters. This Pig Pirate crocheted half mask is great and a little spooky. While they aren’t made of yarn, the DIY Horns were too pretty to pass over.