Day of the Dead Crafts (by Kerry Arquette, Andrea Zocchi, and Jerry Vigil) and their paper mache mask. Basically what you do is attach a plastic theater mask to a balloon and use strips of newspaper and paper mache paste to turn it into a skull. If all goes well, you paint it once it's dry. Unfortunately for me, last year it did not go well at all - you have to use napkins to create the skull's contours over the mask, and I wound up with just a blob. It wasn't even worth painting it.
This year - huzzah! - was a different story. First, I started out with an actual skeleton mask; when we were in Dallas, I found a skeleton Jello mold kit at Tom Thumb that fit the bill. Then I hunted around the Internet to find the best way to paper mache. There are apparently three different methods to making the glue - I decided to go with the heated version (one part flour to four parts water, boiled for three minutes and used when warm), as it's supposed to be stronger.
I ended up making four masks. On the first, the paper mache ended up sticking to the mask, which made it really hard to pull apart. I finally did it but with some slight damage to the side. So on the second go-around, I first laid a paper towel over the mask, and applied the newspaper strips on top of that. It worked pretty well - because of the wetness of the glue, it was fairly easy to get the mushy strips to mold to the skull's shape. Cagatay later suggested using aluminum foil as the bottom layer and that ended up being my favorite, as you can mold it right to the skull and it gave the dried mask a solid weight.