These are tasty, lots of fun to make, and it's a project that works very well with kids. You'll have an easier time of it if you have good candy thermometer, but if you're used to cooking with sugar-based candy, you'll probably be fine without one. The basic method for making popcorn balls is to pop about two cups of kernals, then to place the popped corn in a large lightly oiled bowl (to make clean up easier). You make a basic sugar and butter syrup, then pour it over the popcorn, with any flavorings you want, then, having oiled your hands with butter or oil, you press the popcorn into balls that are no larger than a small apple.

There are endless variations; you can use maple syrup, or honey, instead of sugar to make the syrup. You can use sweet flavorings (orange peel, or lemon zest, chocolate, vanilla, cinnamon) or savory (herbs, cheese, pepper). You can make cotton-ball sized balls to hang on the tree, or you can wrap them in plastic wrap as gifts for family and friends. They'll keep about five days; after that, you might want to share them with the birds.

ChowHound has a basic popcorn ball recipe with step by step instructions, and several variations to get you started: Cocoa-Cayenne popcorn Balls (my favorite), Curry-Cocoanut popcorn Balls, and Eggnog Popcorn Balls. There's a recipe for Carmel Popcorn Balls that's simple and uses Condensed milk for the caramel. Here's one that uses marshmallows and Jello to make brightly Colored Fruit-flavored popcorn balls.

If you want to make them look festive for gift-giving or tying to a tree, you can use colored plastic wrap and bright ribbon to tie it off.