We just had a great Scooby Doo party for my daughter, Joanie, who just turned 5.  It is a great theme for both boys and girls, they all love Scooby.  Joanie always has to have a piñata, so we started with a 70's looking flower piñata. Then we played a Scooby Snack game.  I cut refrigerator biscuits into 6 pieces and rolled them into balls and rolled them in cinnamon-sugar then baked them.  Then I threaded an embroidery needle with dental floss and threaded it through the center of the Scooby snack.  The snacks were hung from a stick and the kids tried to eat their Scooby snacks like Scooby...no hands! But we made sure it wasn't a race, so no one would choke on it. Then we had a hot potato game to the Scooby theme song.  I got a cassette from the library with Cartoon show theme songs and recorded it several times onto a cassette to use for the game. I made a bean bag out of brown material stuffed with popcorn.  Whoever had the Scooby Snack when the music stopped got out of the circle to get a small prize. While the kids were playing hot potato, we set up for the Scooby mystery hunt. Scooby was missing and they had to find him!  It is very easy to incorporate Halloween decorations into a Scooby party.  We hid a Ghost (a white cloth draped over a balloon--the balloon knot is tied onto a hanger, and the cloth is tied at the "neck") it is easiest to put a safety pin into the material and use dental floss to hang in a tree. (dental floss is really strong!) We also hid a spider web, monster mask and a pirate face drawn on a white balloon with a permanent marker and a bandana on it's head.  Clues where hidden in Easter eggs to direct the kids to the next clue. Stuffed Scooby's were hidden in treasure chests near the pirate. The treasure chests were Styrofoam coolers spray painted brown and stuffed with shredded paper. Each team had 4 kids and a team leader to read the clues and help with the searching.  For the treasure hunt the kids each had a costume item to pick from.  The boys had a red scarf (for Freddy) or a Scooby dog tag (blue ribbon with a construction paper yellow and blue diamond shape with SD. Punch a hole in the diamond and use a colored paper club to attach to the ribbon.  Use self sticking Velcro for ribbon closure.) The girls could pick a head band--for Daphne (inexpensive at the Dollar store) or Velma glasses made out of black pipe cleaners. And best of all we got a picture of the Mystery Machine and traced it onto paper.  We had it blown up to 40 x 60 inches at the Copy store and bought foamcore in 40 x 60 at the craft store. You have to trace it for copyright reasons.  Then we colored it and cut the window out so the kids could stick their heads through and look like they were in the Mystery Machine. On the other side we used a blown up picture of The Gang and the kids could stick their heads through and look like they were part of the gang.   They loved all of the games and had a great time!