Got great ideas on this site!  Our party was a huge success! Gave the kids Scooby coloring pages and crayons while guests arrived, but they were hardly touched because we played a Halloween song CD and the kids danced instead.  Everything was already set and I pretended the goodie bags went missing and a note was left. If you want the goodie bags you must crack this case. Work together it's not a race. Scooby and Shaggy say divide into teams. You may see some scary things but please don't scream.  Just follow the clues and you'll do just fine.  Look around and follow the sign."  In the room they were in we hung an 8 x 11 sheet of paper with the word SIGN printed on it and an arrow. They saw it and the fun began. I placed a few paw prints I made on the floor to lead them to the next clue which was taped to the back door. "To get the next clue just grab a bone. You're ready to groove in the mystery zone.  Stand in a line and toss this treat into the bowl where Scooby eats."  In the backyard I had two large dog dishes and put tape down.  Each child took a large milkbone and had to toss it into the dish from behind a line.  When both teams were finished we picked up the bowl and there was the next clue. "Head back inside and go downstairs. You'll see some ghosts but don't be scared.  The ones who stomp and pop the most will get some very special ghosts." I took this idea off the sight.  Blew up white balloons and had the birthday boy draw ghost faces on them. I pulled two aside and the winners from each team got to pop those which of course had the next clue in them. "Scooby says Zoinks...you've done so well so listen up the next clue I'll tell. 6427 is the place to go it's the gangs favorite place to hang ya know.  In the backyard go on the deck. You'll find some puzzles that are a wreck. Put them together and you will see what you and your friends next task will be."  They had to go to our neighbors backyard (again I used paw prints to guide them) where they had to put together 25 piece puzzles.  The next clue was under the table.  "Look around and you will see a white and green place where a car should be.  Go inside and you will find a bunch of things to be combined.  You'll mix and mash and make a brew and soon find out it's Scooby-GOO!". They headed to our garage where we helped them make their own goo to take home. Taped to the glue was the next clue. "An umbrella can block the rain or sun find the big one and have some fun. On the ground you'll see Scooby's head with rings that come in purple not red.  Toss them onto Scooby's ear and have a blast the end is near." I picked up a Scooby ring toss game at the party store for this one.  Under the head was the next clue. "You've worked so hard and deserve a treat but before you get that cake to eat head down stairs and grab a seat. De-code the message you'll get a key. Figure it out and you will see a message for __________ Scooby's biggest fan. Whisper it in ___________'s ear if you can." We used keyboard symbols and made a sheet with the symbols matching letters.  The kids de-coded (with secret message pens of course) and the answer was Happy Birthday _________.  Cake came next followed my presents.  The last present was a card without a name. "Congratulations you've all done great. As detectives go you are first rate. Scooby and the gang are happy you came here are your goodies thanks for playing this game." The note had a map to the goodie-bag location (under a table).  The bags included magnifying glasses and compasses.  We were two hours on the dot."