I had to purchase a new can of monster spray for my li'l guy who's 5. It works wonders with their imagination of monsters in the closet and under the bed. I just print out a googled not too scary picture of a monster and draw a huge circle and line through him. I take room spray (only $1 at some discount stores) and glue on the label I printed. At bedtime we spray the monsters gone and he goes to sleep without an hour of dark room and scary monster fears whew! yay
I did this when my boys were little and YESSSSSSSSSSSSSSSS it works like a charm! Besides you have to love not only $1. but there room smells good *bonus*
my luck my daughter would pick up on the smell good part and know it was just freshener since i use lysol like its going out of style. somewhere i heard of the idea of using a spray bottle with water and glitter in it too.
On the flip side if he thinks the monster is either coming back or not really dead you can always get THIS and tell him see the monster is dead smell him. Warning I heard from other that this stuff is toxic in smell as in the worse they have ever smelled (multi. ppl agreed). I just read about it on my torrent site's forum and it had me laughing. The evil in me wants to get it just to prank someone.

Philly
Do a little dance...