So I got bored the other day and thought I'd try some slow sync flash photographs. In case you forgot, slow sync flash is when you combine flash with a long exposure. In this case, I decided to use rear curtain sync, this means the flash went off at the end of the exposure. You could do this front curtain sync which is where the flash goes off at the beginning and it would give you a very similar result, in this instance anyway.
In this instance, I was using my studio strobe with the modelling light on. The ghost like sections in the photo are from the modelling light whereas the more solid parts are from the flash. If you don't have a studio strobe, you can get something similar by keeping your room lights on and using a flash. The relative intensity of the ghost and solid part depends on the difference the brightness of each of the lights. You may need to adjust your modelling lights and your flash powers to get the effect you want. Otherwise, one may simply overpower the other and you won't get the same effect.
Remember you can combine the effects of slow sync flash with zoom bursts and general camera movement to be able to create more dynamic images.