Megan's munchies has the cutest ghostly cereal treats. They were even published on bettycrocker.com!
Get the instructions here:
http://megansmunchies.com/ghostly-cereal-treats/
Teach mama has a great way to turn a frozen banana into a spooky ghost. All you need is to dip them in white chocolate.
Get the instructions here:
http://teachmama.com/2010/10/super-easy-super-spooky-halloween.html
Beautifully wonderful life uses a cookie to make her spooky ghosts.
Get the instructions here:
http://beautifullywonderfullife.wordpress.com/2011/10/28/spooky-treats/