This website is the best it really gave me inspiration.  Though I was able to use some ideas in here I had one problem, having a successful party on a three and four year old level.  It was a success. As the kids arrived I had the b-day boy greet his guest and take each present and put in a specific box.  While guest were arriving the kids played beanbag toss with beanbags that I had made from scooby fabric and I took a box and had traced scooby on it and cut a hole big enough for a bean bag through his mouth. While the kids were occupied dad took all the presents and hid them. We then played spooky music in room where the present were and told all the kids that it was time to open presents, to find out the presents were gone.  Left in place of the presents was a clue - a casette tape(got a battery operated preschool tape player)the kids put the casette tape in the tape player and listened.  On the tape was a story about a birthday ghost haunting the house, Oh no! The ghost has stolen all the b-day gifts! You will have to follow the clues to find the b-day presents.  LISTEN "There is a ghost in the room of play(this can be a room that works best for you)knock him down and he'll show you the way." The ghost was a ghost pinata. In the pinata out came goody bags I already made up for the amount of kids and a casette tape. The kids knew exactly what to do with the tape and all ran to the casette player and listened.  GOOD JOB GANG, here is your second clue "You must pin the bone in scooby's mouth and then you will see." After each child had a turn they got another casette tape.  JINKIES, YOU GUYS ARE GOOD! but there is still a mystery to be solved, the birthday gifts are still gone!  ZOINKS! Listen up gang "Go to the place where you would eat for a scooby snack, maybe even a piece of cake." and there you will find your next clue."  Then they ate cake and ice cream where the next casette tape was.  SCOOBY DOOBY DOO! Listen here, "With so many friends to help you out, you'll solve this mystery with out a doubt!  Go to the place where you seen a ghost , I know you can!" and maybe you will see who the b-day ghost may be. When kids run to where the pinata was we had dad dressed up in a mask and the kids took off his mask to find out it wasnt a ghost after all it was just dad. Then dad said the famous words " I would of gotten away with it, if it wasnt for you meddling kids!"  It was a great time.