Since a few of you asked, I thought I'd share how I made the "floating" specters I used in my Ghostbusters display this year. It's pretty simple to recreate and because of its size, has a great impact.
You'll need: pvc pipe + connectors + glue, chicken wire, black cloth, cheese cloth, black gloves, thin gauge wire to attaching the cloth to the chicken wire frame, thicker gauge wire to use to form the hands. If you don't have dirt to stake the pipe into, you'll also need a bucket and cement to create a base.
1. Create the armature using the pvc pipe and connectors. I didn't measure anything exactly, just use own body to estimate the size of the shoulders and arms. Glue together. (If you are using the bucket stand method, now is a good time to set that up.)
2. Create a hooded shape and shoulders using chicken wire. Again, I didn't measure anything exactly, just cut out a large piece and shaped it until it looked approximately right.
3. Once you are happy with that shape, cut out a piece of black fabric and attach it to the inside of the "hood" using the thin gauge wire.
4. Wrap the arms of your specter with cheesecloth tying off the ends. You'll add more fabric on top of this wrap to create bulk but you want to hide the pvc well.
5. Drape pieces of cheesecloth on the head and wrap ends around shoulders and arms to create a draped look. The goal is to completely hide the chicken wire and pipe. The more cheesecloth you add, the better it looks.
6. Cut, bend and knot 5 pieces of wire to create a hand shape. Stuff inside of glove and then shove into the end of pvc pipe using the knot to keep snug. (I wanted the specters to be holding something so the bendable wire was important. If you were just going to have their hands extended, you could just stuff the gloves with anything to keep stiff and wire to the frame.)
7. Add more cheesecloth over the arms to cover the hem of the gloves.
8. Tear the edges of the cheesecloth to create a tattered effect.
9. Pose your ghost behind something so that the supporting pole is hidden and your ghost appears to float.
So there you have it! If you search online you will find much more elaborate (and more impressive) versions of this project. This was perfect for what I needed it for but the options to make it more ghoulish are endless!